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Jonathan S Lindsey - One of the best experts on this subject based on the ideXlab platform.
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bacteriochlorin bis spermine conjugate affords an effective photodynamic action to eradicate microorganisms
Journal of Biophotonics, 2020Co-Authors: Maria Belen Ballatore, Jonathan S Lindsey, Maria Elisa Milanesio, Hikaru Fujita, Edgardo N DurantiniAbstract:A novel bacteriochlorin bearing two spermine units (BCS) was synthesized from 3,13-dibromo-8,8,18,18-tetramethylbacteriochlorin (BC-Br 3,13 ). The synthesis involved the Suzuki coupling of BC-Br 3,13 to obtain a bacteriochlorin-dibenzaldehyde (BCA), which was subjected to reductive amination with spermine. The resulting bacteriochlorin BCS presents a strong near-infrared absorption band at 747 nm, emits at 750 nm with fluorescence quantum yield of 0.14, and generates singlet molecular oxygen, O2 (1 Δg ), with a quantum yield of 0.27. Photokilling capacities mediated by BCS were evaluated in microbial cells. The viability of Staphylococcus aureus decreased 7 logs when cells were incubated with 1 μM BCS and irradiated for 15 minutes. Comparable photocytotoxic effect was obtained with Escherichia coli, when cells were treated for 30 minutes with visible light. BCS was also an effective photosensitizer to inactivate Candida albicans. In addition, this bacteriochlorin was able to eradicate bacteria at short incubation times. The structure of BCS contains eight basic amino groups that, when protonated in water, increase the binding to the cell envelope. In summary, the readily accessible bacteriochlorin BCS was highly effective at low concentrations as a broad-spectrum antimicrobial photosensitizer.
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synthesis of tailored hydrodipyrrins and their examination in directed routes to Bacteriochlorins and tetradehydrocorrins
New Journal of Chemistry, 2017Co-Authors: Shaofei Zhang, Olga Mass, Hanje Kim, Muthyala Nagarjuna Reddy, Jonathan S LindseyAbstract:The chemistry of reduced tetrapyrroles is less developed than that of the fully unsaturated (porphyrin) analogues, yet is of comparable importance given the natural roles of hydroporphyrins (e.g., chlorophylls, bacteriochlorophylls) and contracted hydroporphyrins (cobalamin). The self-condensation of a 1-(dimethoxymethyl)-2,3-dihydro-3,3-dimethyldipyrrin (termed a dihydrodipyrrin-acetal) affords the corresponding bacteriochlorin or tetradehydrocorrin with the outcome potentially controllable by choice of the catalysis conditions. The ability to install distinct patterns of substituents about the perimeter of the synthetic macrocycles is essential for biomimetic studies. Here, 18 new target (and 9 intermediate) hydrodipyrrins encompassing a range of dipyrrin saturation levels (dihydro, tetrahydro, hexahydro) and equipped with diverse α-pyrrole (-H, -SMe, -SPh, -Br, -Me, -CO2R, dioxaborolanyl) and α-pyrroline (methyl, formyl, dimethoxymethyl, oxo, methoxy, methylthio, iminomethyl, ethoxycarbonylvinyl, dicyanovinyl) substituents have been prepared and examined in the directed synthesis of Bacteriochlorins. The routes – inspired by a directed route to chlorins – rely on condensation of two hydrodipyrrins to produce a hydrobilin followed by ring closure to form the macrocycle. Four new unsymmetrically substituted Bacteriochlorins were obtained in very low yields; as an offshoot, efficient routes to three new tetradehydrocorrins (nickel chelates) were discovered, including two B,D-tetradehydrocorrins (pyrroline–pyrrole A–D ring junction) and one B,C-tetradehydrocorrin (pyrroline–pyrroline A–D ring junction). Taken together, this study deepens our understanding of the chemistry of hydrodipyrrins and hydrobilins as precursors to hydroporphyrins.
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synthesis and photophysical characterization of Bacteriochlorins equipped with integral swallowtail substituents
New Journal of Chemistry, 2017Co-Authors: Yizhou Liu, David F Bocian, Dewey Holten, James R Diers, Muthyala Nagarjuna Reddy, Srinivasarao Allu, Don Hood, Jonathan S LindseyAbstract:Bacteriochlorins such as bacteriochlorophyll a absorb strongly in the near-infrared spectral region and are potentially useful in a variety of photochemical fields. De novo syntheses of Bacteriochlorins entail self-condensation of a dihydrodipyrrin-acetal (containing one pyrrole and one pyrroline joined via a methylidene bridge) either via a heavily studied Eastern–Western (E–W) route or a recently reported Northern–Southern (N–S) route. The Michael addition to form the dihydrodipyrrin-acetal for the E–W approach has limited scope for the installation of substituents on the pyrroline units. By use of the N–S route, new Bacteriochlorins have been prepared that bear a pair of aryl or alkyl groups, together termed a “swallowtail” substituent, at each β-pyrroline unit, a previously inaccessible design. Single-crystal X-ray structures of three intermediates were determined. Bacteriochlorins synthesized herein exhibit characteristic bacteriochlorophyll-like absorption spectra, including a Qy band in the region of 730–758 nm. The swallowtail groups have little impact on the excited-state properties of the Bacteriochlorins, and the slight changes of spectral properties that are observed stem from substituent electronic effects rather than changes in structure. In summary, introduction of an integral swallowtail unit on the pyrroline ring opens new sites for tailoring molecular designs without altering the attractive photophysical features of the synthetic Bacteriochlorins.
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construction of the bacteriochlorin macrocycle with concomitant nazarov cyclization to form the annulated isocyclic ring analogues of bacteriochlorophyll a
Journal of Organic Chemistry, 2017Co-Authors: Shaofei Zhang, Jonathan S LindseyAbstract:Bacteriochlorophylls contain a bacteriochlorin macrocycle bearing an annulated fifth ring. The fifth ring, termed the isocyclic ring or ring E, is equipped with 131-oxo and 132-carbomethoxy substituents. Herein, a general route to stable, synthetic bacteriochlorophyll analogues is described. Knoevenagel condensation (∼40 mM, rt, CH2Cl2, piperidine/AcOH/molecular sieves) of a dihydrodipyrrin–carboxaldehyde (AD half) and a dihydrodipyrrin substituted with a β-ketoester (BC half) forms a propenone bearing the two halves (a hydrobilin analogue). Subsequent treatment (0.2 mM) with acid (Yb(OTf)3, CH3CN, 80 °C) promotes a double ring-closure process: (i) condensation between the α-position of pyrrole ring A and the α-acetal unit attached to pyrroline ring B forms the bacteriochlorin macrocycle, and (ii) Nazarov cyclization of the β-(propenoyl)-substituted ring C forms the isocyclic ring (E). Five new Bacteriochlorins bearing various substituents (alkyl/alkyl, aryl, and alkyl/ester) at positions 2 and 3 (β-pyrro...
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Construction of the Bacteriochlorin Macrocycle with Concomitant Nazarov Cyclization To Form the Annulated Isocyclic Ring: Analogues of Bacteriochlorophyll a
2017Co-Authors: Shaofei Zhang, Jonathan S LindseyAbstract:Bacteriochlorophylls contain a bacteriochlorin macrocycle bearing an annulated fifth ring. The fifth ring, termed the isocyclic ring or ring E, is equipped with 131-oxo and 132-carbomethoxy substituents. Herein, a general route to stable, synthetic bacteriochlorophyll analogues is described. Knoevenagel condensation (∼40 mM, rt, CH2Cl2, piperidine/AcOH/molecular sieves) of a dihydrodipyrrin–carboxaldehyde (AD half) and a dihydrodipyrrin substituted with a β-ketoester (BC half) forms a propenone bearing the two halves (a hydrobilin analogue). Subsequent treatment (0.2 mM) with acid (Yb(OTf)3, CH3CN, 80 °C) promotes a double ring-closure process: (i) condensation between the α-position of pyrrole ring A and the α-acetal unit attached to pyrroline ring B forms the bacteriochlorin macrocycle, and (ii) Nazarov cyclization of the β-(propenoyl)-substituted ring C forms the isocyclic ring (E). Five new Bacteriochlorins bearing various substituents (alkyl/alkyl, aryl, and alkyl/ester) at positions 2 and 3 (β-pyrrole sites, ring A) and 132 carboalkoxy groups (R = Me or Et) were constructed in 37–61% yield from the hydrobilin analogues. The BC half and AD half are available in five and eight steps, respectively, from the corresponding pyrrole-2-carboxaldehyde and unsaturated ketone. The Bacteriochlorins exhibit absorption spectra typical of bacteriopheophytins (free base bacteriochlorophylls), with a strong near-infrared absorption band (707–751 nm)
Marcin Ptaszek - One of the best experts on this subject based on the ideXlab platform.
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excitonic interactions in bacteriochlorin homo dyads enable charge transfer a new approach to the artificial photosynthetic special pair
Journal of Physical Chemistry B, 2018Co-Authors: Christopher Mccleese, Nopondo N Esemoto, Charles Kolodziej, Buddhadev Maiti, Srijana Bhandari, Barry D Dunietz, Clemens Burda, Marcin PtaszekAbstract:Excitonically coupled bacteriochlorin (BC) dimers constitute a primary electron donor (special pair) in bacterial photosynthesis and absorbing units in light-harvesting antenna. However, the exact nature of the excited state of these dyads is still not fully understood. Here, we report a detailed spectroscopic and computational investigation of a series of symmetrical bacteriochlorin dimers, where the Bacteriochlorins are connected either directly or by a phenylene bridge of variable length. The excited state of these dyads is quenched in high-dielectric solvents, which we attribute to photoinduced charge transfer. The mixing of charge transfer with the excitonic state causes accelerated (within 41 ps) decay of the excited state for the directly linked dyad, which is reduced by orders of magnitude with each additional phenyl ring separating the Bacteriochlorins. These results highlight the origins of the excited-state dynamics in symmetric BC dyads and provide a new model for studying the primary processe...
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Excitonic Interactions in Bacteriochlorin Homo-Dyads Enable Charge Transfer: A New Approach to the Artificial Photosynthetic Special Pair
2018Co-Authors: Christopher Mccleese, Nopondo N Esemoto, Charles Kolodziej, Buddhadev Maiti, Srijana Bhandari, Barry D Dunietz, Clemens Burda, Marcin PtaszekAbstract:Excitonically coupled bacteriochlorin (BC) dimers constitute a primary electron donor (special pair) in bacterial photosynthesis and absorbing units in light-harvesting antenna. However, the exact nature of the excited state of these dyads is still not fully understood. Here, we report a detailed spectroscopic and computational investigation of a series of symmetrical bacteriochlorin dimers, where the Bacteriochlorins are connected either directly or by a phenylene bridge of variable length. The excited state of these dyads is quenched in high-dielectric solvents, which we attribute to photoinduced charge transfer. The mixing of charge transfer with the excitonic state causes accelerated (within 41 ps) decay of the excited state for the directly linked dyad, which is reduced by orders of magnitude with each additional phenyl ring separating the Bacteriochlorins. These results highlight the origins of the excited-state dynamics in symmetric BC dyads and provide a new model for studying the primary processes in photosynthesis and for the development of artificial, biomimetic systems for solar energy conversion
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bodipy bacteriochlorin energy transfer arrays toward near ir emitters with broadly tunable multiple absorption bands
Journal of Organic Chemistry, 2017Co-Authors: Adam Meares, Andrius Satraitis, Marcin PtaszekAbstract:A series of energy transfer arrays, comprising a near-IR absorbing and emitting bacteriochlorin, and BODIPY derivatives with different absorption bands in the visible region (503–668 nm) have been synthesized. Absorption band of BODIPY was tuned by installation of 0, 1, or 2 styryl substituents [2-(2,4,6-trimethoxyphenyl)ethenyl], which leads to derivatives with absorption maxima at 503, 587, and 668 nm, respectively. Efficient energy transfer (>0.90) is observed for each dyad, which is manifested by nearly exclusive emission from bacteriochlorin moiety upon BODIPY excitation. Fluorescence quantum yield of each dyad in nonpolar solvent (toluene) is comparable with that observed for corresponding bacteriochlorin monomer, and is significantly reduced in solvent of high dielectric constants (DMF), most likely by photoinduced electron transfer. Given the availability of diverse BODIPY derivatives, with absorption between 500–700 nm, BODIPY–bacteriochlorin arrays should allow for construction of near-IR emitti...
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Symmetrical and Nonsymmetrical Meso–Meso Directly Linked Hydroporphyrin Dyads: Synthesis and Photochemical Properties
2017Co-Authors: Nopondo N Esemoto, Andrius Satraitis, Linda Wiratan, Marcin PtaszekAbstract:A series of a rigid meso–meso directly linked chlorin–chlorin, chlorin–bacteriochlorin, and bacteriochlorin–bacteriochlorin dyads, including free bases as well as Zn(II), Pd(II), and Cu(II) complexes, has been synthesized, and their absorption, emission, singlet oxygen (1O2) photosensitization, and electronic properties have been examined. Marked bathochromic shifts of the long-wavelength Qy absorption band and increase in fluorescence quantum yields in dyads, in comparison to the corresponding monomers, are observed. Nonsymmetrical dyads (except bacteriochlorin–bacteriochlorin) show two distinctive Qy bands, corresponding to the absorption of each dyad component. A nearly quantitative S1–S1 energy transfer between hydroporphyrins in dyads, leading to an almost exclusive emission of hydroporphyrin with a lower S1 energy, has been determined. Several symmetrical and all nonsymmetrical dyads exhibit a significant reduction in fluorescence quantum yields in solvents of high dielectric constants; this is attributed to the photoinduced electron transfer. The complexation of one macrocycle by Cu(II) or Pd(II) enhances intersystem crossing in the adjacent, free base dyad component, which is manifested by a significant reduction in fluorescence and increase in quantum yield of 1O2 photosensitization
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BODIPY–Bacteriochlorin Energy Transfer Arrays: Toward Near-IR Emitters with Broadly Tunable, Multiple Absorption Bands
2017Co-Authors: Adam Meares, Andrius Satraitis, Marcin PtaszekAbstract:A series of energy transfer arrays, comprising a near-IR absorbing and emitting bacteriochlorin, and BODIPY derivatives with different absorption bands in the visible region (503–668 nm) have been synthesized. Absorption band of BODIPY was tuned by installation of 0, 1, or 2 styryl substituents [2-(2,4,6-trimethoxyphenyl)ethenyl], which leads to derivatives with absorption maxima at 503, 587, and 668 nm, respectively. Efficient energy transfer (>0.90) is observed for each dyad, which is manifested by nearly exclusive emission from bacteriochlorin moiety upon BODIPY excitation. Fluorescence quantum yield of each dyad in nonpolar solvent (toluene) is comparable with that observed for corresponding bacteriochlorin monomer, and is significantly reduced in solvent of high dielectric constants (DMF), most likely by photoinduced electron transfer. Given the availability of diverse BODIPY derivatives, with absorption between 500–700 nm, BODIPY–bacteriochlorin arrays should allow for construction of near-IR emitting agents with multiple and broadly tunable absorption bands. Solvent-dielectric constant dependence of Φf in dyads gives an opportunity to construct environmentally sensitive fluorophores and probes
Dewey Holten - One of the best experts on this subject based on the ideXlab platform.
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synthesis and photophysical characterization of Bacteriochlorins equipped with integral swallowtail substituents
New Journal of Chemistry, 2017Co-Authors: Yizhou Liu, David F Bocian, Dewey Holten, James R Diers, Muthyala Nagarjuna Reddy, Srinivasarao Allu, Don Hood, Jonathan S LindseyAbstract:Bacteriochlorins such as bacteriochlorophyll a absorb strongly in the near-infrared spectral region and are potentially useful in a variety of photochemical fields. De novo syntheses of Bacteriochlorins entail self-condensation of a dihydrodipyrrin-acetal (containing one pyrrole and one pyrroline joined via a methylidene bridge) either via a heavily studied Eastern–Western (E–W) route or a recently reported Northern–Southern (N–S) route. The Michael addition to form the dihydrodipyrrin-acetal for the E–W approach has limited scope for the installation of substituents on the pyrroline units. By use of the N–S route, new Bacteriochlorins have been prepared that bear a pair of aryl or alkyl groups, together termed a “swallowtail” substituent, at each β-pyrroline unit, a previously inaccessible design. Single-crystal X-ray structures of three intermediates were determined. Bacteriochlorins synthesized herein exhibit characteristic bacteriochlorophyll-like absorption spectra, including a Qy band in the region of 730–758 nm. The swallowtail groups have little impact on the excited-state properties of the Bacteriochlorins, and the slight changes of spectral properties that are observed stem from substituent electronic effects rather than changes in structure. In summary, introduction of an integral swallowtail unit on the pyrroline ring opens new sites for tailoring molecular designs without altering the attractive photophysical features of the synthetic Bacteriochlorins.
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photophysical comparisons of pegylated porphyrins chlorins and Bacteriochlorins in water
New Journal of Chemistry, 2016Co-Authors: Amit Kumar Mandal, David F Bocian, Jonathan S Lindsey, Mengran Liu, Tuba Sahin, Dewey HoltenAbstract:Comparison of the photophysics of analogous members of the porphyrin, chlorin, and bacteriochlorin family has rarely been carried out, and most studies of individual members have been performed in non-aqueous media. Advances in synthesis and molecular design now enable such comparative studies in aqueous solution. A water-soluble bioconjugatable free base porphyrin (FbP1) has been synthesized, complementing recently prepared chlorin and bacteriochlorin analogues. The porphyrin (a trans-AB architecture; i.e., 5,15-substitution pattern) is equipped with one meso-aryl group that bears three short polyethylene glycol (PEG) substituents at the 2,4,6-positions for aqueous solubility, and one meso-aryl group that bears an oxyacetic acid group at the p-position for bioconjugation. Spectroscopic examination of porphyrin FbP1 gave the following quantum yields in DMF versus water: fluorescence (Φf = 0.077 vs. 0.066), intersystem crossing (Φisc = 0.90 vs. 0.84), and internal conversion (Φic = 0.023 vs. 0.094). The increase in Φic upon moving from DMF into water reflects the 4-fold increase in rate constant for internal conversion, from (600 ns)−1 to (140 ns)−1. Photophysical comparisons (τS, kf, kic, kisc, Φf, Φic, Φisc) were made with analogous chlorins and Bacteriochlorins in DMF and water. The value of kic in both media increases in the order (visible-absorbing) porphyrin < (red-absorbing) chlorin < (near-infrared-absorbing) bacteriochlorin, consistent with the general S1-energy dependence of kic expected on the basis of the energy-gap law for non-radiative decay. In summary, there are now satisfactory molecular designs, viable synthetic routes, and thoroughly characterized photophysical properties that permit aqueous solution studies of a complement of porphyrins, chlorins, and Bacteriochlorins.
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bioconjugatable pegylated hydroporphyrins for photochemistry and photomedicine narrow band near infrared emitting Bacteriochlorins
New Journal of Chemistry, 2016Co-Authors: Nuonuo Zhang, Jianbing Jiang, David F Bocian, Dewey Holten, Masahiko Taniguchi, Amit Kumar Mandal, Rosemary B Evansstorms, Bruce J Pitner, Jonathan S LindseyAbstract:Synthetic Bacteriochlorins absorb in the near-infrared (NIR) region and are versatile analogues of natural bacteriochlorophylls. The utilization of these chromophores in energy sciences and photomedicine requires the ability to tailor their physicochemical properties, including the incorporation of units to impart water solubility. Herein, we report the synthesis, from two common bacteriochlorin building blocks, of five wavelength-tunable, bioconjugatable and water-soluble Bacteriochlorins along with two non-bioconjugatable benchmarks. Each bacteriochlorin bears short polyethylene glycol (PEG) units as the water-solubilizing motif. The PEG groups are located at the 3,5-positions of aryl groups at the pyrrolic β-positions to suppress aggregation in aqueous media. A handle containing a single carboxylic acid is incorporated to allow bioconjugation. The seven water-soluble Bacteriochlorins in water display Qy absorption into the NIR range (679-819 nm), sharp emission (21-36 nm full-width-at-half-maximum) and modest fluorescence quantum yield (0.017-0.13). Each bacteriochlorin is neutral (non-ionic) yet soluble in organic (e.g., CH2Cl2, DMF) and aqueous solutions. Water solubility was assessed using absorption spectroscopy by changing the concentration ∼1000-fold (190-690 µM to 0.19-0.69 µM) with a reciprocal change in pathlength (0.1-10 cm). All Bacteriochlorins showed excellent solubility in water, except for a bacteriochlorin-imide that gave slight aggregation at higher concentrations. One bacteriochlorin was conjugated to a mouse polyclonal IgG antibody for use in flow cytometry with compensation beads for proof-of-principle. The antibody conjugate of B2-NHS displayed a sharp signal upon ultraviolet laser excitation (355 nm) with NIR emission measured with a 730/45 nm bandpass filter. Overall, the study gives access to a set of water-soluble Bacteriochlorins with desirable photophysical properties for use in multiple fields.
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Synthesis and Physicochemical Properties of MetalloBacteriochlorins
2016Co-Authors: Chih-yuan Chen, David F Bocian, Dewey Holten, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Dazhong Fan, Erjun Sun, Brian E. Mcdowell, Jonathan S LindseyAbstract:Access to metalloBacteriochlorins is essential for investigation of a wide variety of fundamental photochemical processes, yet relatively few synthetic metalloBacteriochlorins have been prepared. Members of a set of synthetic Bacteriochlorins bearing 0–4 carbonyl groups (1, 2, or 4 carboethoxy substituents, or an annulated imide moiety) were examined under two conditions: (i) standard conditions for zincation of porphyrins [Zn(OAc)2·2H2O in N,N-dimethylformamide (DMF) at 60–80 °C], and (ii) treatment in tetrahydrofuran (THF) with a strong base [e.g., NaH or lithium diisopropylamide (LDA)] followed by a metal reagent MXn. Zincation of Bacteriochlorins that bear 2–4 carbonyl groups proceeded under the former method whereas those with 0–2 carbonyl groups proceeded with NaH or LDA/THF followed by Zn(OTf)2. The scope of metalation (via NaH or LDA in THF) is as follows: (a) for Bacteriochlorins that bear two electron-releasing aryl groups, M = Cu, Zn, Pd, and InCl (but not Mg, Al, Ni, Sn, or Au); (b) for Bacteriochlorins that bear two carboethoxy groups, M = Ni, Cu, Zn, Pd, Cd, InCl, and Sn (but not Mg, Al, or Au); and (c) a bacteriochlorin with four carboethoxy groups was metalated with Mg (other metals were not examined). Altogether, 15 metalloBacteriochlorins were isolated and characterized. Single-crystal X-ray analysis of 8,8,18,18-tetramethylbacteriochlorin reveals the core geometry provided by the four nitrogen atoms is rectangular; the difference in length of the two sides is ∼0.08 Å. Electronic characteristics of (metal-free) Bacteriochlorins were probed through electrochemical measurements along with density functional theory calculation of the energies of the frontier molecular orbitals. The photophysical properties (fluorescence yields, triplet yields, singlet and triplet excited-state lifetimes) of the zinc Bacteriochlorins are generally similar to those of the metal-free analogues, and to those of the native chromophores bacteriochlorophyll a and bacteriopheophytin a. The availability of diverse metalloBacteriochlorins should prove useful in a variety of fundamental photochemical studies and applications
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integration of cyanine merocyanine and styryl dye motifs with synthetic Bacteriochlorins
Photochemistry and Photobiology, 2016Co-Authors: Eunkyung Yang, Christine Kirmaier, David F Bocian, Jonathan S Lindsey, Masahiko Taniguchi, James R Diers, Nuonuo Zhang, Michael Krayer, Dewey HoltenAbstract:: Understanding the effects of substituents on spectral properties is essential for the rational design of tailored Bacteriochlorins for light-harvesting and other applications. Toward this goal, three new Bacteriochlorins containing previously unexplored conjugating substituents have been prepared and characterized. The conjugating substituents include two positively charged species, 2-(N-ethyl 2-quinolinium)vinyl- (B-1) and 2-(N-ethyl 4-pyridinium)vinyl- (B-2), and a neutral group, acroleinyl- (B-3); the charged species resemble cyanine (or styryl) dye motifs whereas the neutral unit resembles a merocyanine dye motif. The three Bacteriochlorins are examined by static and time-resolved absorption and emission spectroscopy and density functional theoretical calculations. B-1 and B-2 have Qy absorption bathochromically shifted well into the NIR region (822 and 852 nm), farther than B-3 (793 nm) and other 3,13-disubstituted Bacteriochlorins studied previously. B-1 and B-2 have broad Qy absorption and fluorescence features with large peak separation (Stokes shift), low fluorescence yields, and shortened S1 (Qy ) excited-state lifetimes (~700 ps and ~100 ps). More typical spectra and S1 lifetime (~2.3 ns) are found for B-3. The combined photophysical and molecular-orbital characteristics suggest the altered spectra and enhanced nonradiative S1 decay of B-1 and B-2 derive from excited-state configurations in which electron density is shifted between the macrocycle and the substituents.
Eunkyung Yang - One of the best experts on this subject based on the ideXlab platform.
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integration of cyanine merocyanine and styryl dye motifs with synthetic Bacteriochlorins
Photochemistry and Photobiology, 2016Co-Authors: Eunkyung Yang, Christine Kirmaier, David F Bocian, Jonathan S Lindsey, Masahiko Taniguchi, James R Diers, Nuonuo Zhang, Michael Krayer, Dewey HoltenAbstract:: Understanding the effects of substituents on spectral properties is essential for the rational design of tailored Bacteriochlorins for light-harvesting and other applications. Toward this goal, three new Bacteriochlorins containing previously unexplored conjugating substituents have been prepared and characterized. The conjugating substituents include two positively charged species, 2-(N-ethyl 2-quinolinium)vinyl- (B-1) and 2-(N-ethyl 4-pyridinium)vinyl- (B-2), and a neutral group, acroleinyl- (B-3); the charged species resemble cyanine (or styryl) dye motifs whereas the neutral unit resembles a merocyanine dye motif. The three Bacteriochlorins are examined by static and time-resolved absorption and emission spectroscopy and density functional theoretical calculations. B-1 and B-2 have Qy absorption bathochromically shifted well into the NIR region (822 and 852 nm), farther than B-3 (793 nm) and other 3,13-disubstituted Bacteriochlorins studied previously. B-1 and B-2 have broad Qy absorption and fluorescence features with large peak separation (Stokes shift), low fluorescence yields, and shortened S1 (Qy ) excited-state lifetimes (~700 ps and ~100 ps). More typical spectra and S1 lifetime (~2.3 ns) are found for B-3. The combined photophysical and molecular-orbital characteristics suggest the altered spectra and enhanced nonradiative S1 decay of B-1 and B-2 derive from excited-state configurations in which electron density is shifted between the macrocycle and the substituents.
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Synthesis and Physicochemical Properties of MetalloBacteriochlorins
2016Co-Authors: Chih-yuan Chen, David F Bocian, Dewey Holten, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Dazhong Fan, Erjun Sun, Brian E. Mcdowell, Jonathan S LindseyAbstract:Access to metalloBacteriochlorins is essential for investigation of a wide variety of fundamental photochemical processes, yet relatively few synthetic metalloBacteriochlorins have been prepared. Members of a set of synthetic Bacteriochlorins bearing 0–4 carbonyl groups (1, 2, or 4 carboethoxy substituents, or an annulated imide moiety) were examined under two conditions: (i) standard conditions for zincation of porphyrins [Zn(OAc)2·2H2O in N,N-dimethylformamide (DMF) at 60–80 °C], and (ii) treatment in tetrahydrofuran (THF) with a strong base [e.g., NaH or lithium diisopropylamide (LDA)] followed by a metal reagent MXn. Zincation of Bacteriochlorins that bear 2–4 carbonyl groups proceeded under the former method whereas those with 0–2 carbonyl groups proceeded with NaH or LDA/THF followed by Zn(OTf)2. The scope of metalation (via NaH or LDA in THF) is as follows: (a) for Bacteriochlorins that bear two electron-releasing aryl groups, M = Cu, Zn, Pd, and InCl (but not Mg, Al, Ni, Sn, or Au); (b) for Bacteriochlorins that bear two carboethoxy groups, M = Ni, Cu, Zn, Pd, Cd, InCl, and Sn (but not Mg, Al, or Au); and (c) a bacteriochlorin with four carboethoxy groups was metalated with Mg (other metals were not examined). Altogether, 15 metalloBacteriochlorins were isolated and characterized. Single-crystal X-ray analysis of 8,8,18,18-tetramethylbacteriochlorin reveals the core geometry provided by the four nitrogen atoms is rectangular; the difference in length of the two sides is ∼0.08 Å. Electronic characteristics of (metal-free) Bacteriochlorins were probed through electrochemical measurements along with density functional theory calculation of the energies of the frontier molecular orbitals. The photophysical properties (fluorescence yields, triplet yields, singlet and triplet excited-state lifetimes) of the zinc Bacteriochlorins are generally similar to those of the metal-free analogues, and to those of the native chromophores bacteriochlorophyll a and bacteriopheophytin a. The availability of diverse metalloBacteriochlorins should prove useful in a variety of fundamental photochemical studies and applications
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synthetic Bacteriochlorins bearing polar motifs carboxylate phosphonate ammonium and a short peg water solubilization bioconjugation and photophysical properties
New Journal of Chemistry, 2015Co-Authors: Jianbing Jiang, Dariusz M Niedzwiedzki, Christine Kirmaier, David F Bocian, Dewey Holten, Eunkyung Yang, Kanumuri Ramesh Reddy, Jonathan S LindseyAbstract:Bacteriochlorins are potentially excellent chromophores for near-infrared (NIR) photochemical and spectroscopic studies yet the intrinsically hydrophobic macrocycle core has stymied work in aqueous media. Herein, a set of Bacteriochlorins bearing distinct polar motifs is reported. The motifs include phosphonate (pH-dependent anionic, BC1), carboxylate (pH-dependent anionic, BC2), ammonium (permanently cationic) without (BC3) or with (BC4) a linker ester moiety, and tetraethyleneoxy (a short PEG, polar non-ionic, BC5). The groups are located at the 3,5-positions of each of two aryl groups at the bacteriochlorin 3,13-sites. Synthesis of the Bacteriochlorins entails the Suzuki coupling of a common 3,13-dibromobacteriochlorin building block with a set of aryl boronates. Five factors were selected for comparisons among the polar motifs upon attachment to the Bacteriochlorins: (1) synthesis yield and ease of purification, (2) amenability toward subsequent derivatization, (3) water-solubility, (4) full-width-at-half-maximum (fwhm) of the long-wavelength (Qy) absorption and fluorescence bands, singlet excited-state lifetime (τS) and fluorescence quantum yield (Φf), and (5) stability in the dark or under illumination. Water-solubility was assessed by examination of the absorption spectra across a 1000-fold concentration range (∼0.2–0.6 μM to ∼200–600 μM). With the exception of BC4, all displayed good aqueous solubility, photostability, and photophysical properties in aqueous solution (fwhm = 23–31 nm, Φf = 0.10–0.16, τS = 1.9–2.7 ns). The modestly lower Φf and τS values for the Bacteriochlorins in aqueous versus organic (N,N-dimethylformamide) media are traced to an increased rate constant for excited-state internal conversion. Upon consideration of all factors, the ammonium (short linker) and short PEG groups were most attractive for solubilization of the Bacteriochlorins in aqueous media. The studies prompted the synthesis of two water-soluble (ammonium-substituted) Bacteriochlorins bearing N-hydroxysuccinimide esters.
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extending the short and long wavelength limits of bacteriochlorin near infrared absorption via dioxo and bisimide functionalization
Journal of Physical Chemistry B, 2015Co-Authors: Pothiappan Vairaprakash, Dariusz M Niedzwiedzki, Christine Kirmaier, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Tuba Sahin, Michael Krayer, Alfred Wang, Jonathan S LindseyAbstract:Six new Bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin–bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin–bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin–monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin–monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer si...
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Extending the Short and Long Wavelength Limits of Bacteriochlorin Near-Infrared Absorption via Dioxo- and Bisimide-Functionalization
2015Co-Authors: Pothiappan Vairaprakash, Dariusz M Niedzwiedzki, Christine Kirmaier, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Tuba Sahin, Michael Krayer, Alfred Wang, Jonathan S LindseyAbstract:Six new Bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin–bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin–bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin–monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin–monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer singlet excited-state lifetime (∼4 ns vs ∼2 ns). The photophysical enhancements derive in part from mixing of the lowest unoccupied frontier molecular orbitals of the five-membered imide ring with those of the bacteriochlorin framework. In general, all of the new Bacteriochlorins have excited-state lifetimes (1–4 ns) that are sufficiently long for use in molecular-based systems for photochemical applications
Michael Krayer - One of the best experts on this subject based on the ideXlab platform.
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integration of cyanine merocyanine and styryl dye motifs with synthetic Bacteriochlorins
Photochemistry and Photobiology, 2016Co-Authors: Eunkyung Yang, Christine Kirmaier, David F Bocian, Jonathan S Lindsey, Masahiko Taniguchi, James R Diers, Nuonuo Zhang, Michael Krayer, Dewey HoltenAbstract:: Understanding the effects of substituents on spectral properties is essential for the rational design of tailored Bacteriochlorins for light-harvesting and other applications. Toward this goal, three new Bacteriochlorins containing previously unexplored conjugating substituents have been prepared and characterized. The conjugating substituents include two positively charged species, 2-(N-ethyl 2-quinolinium)vinyl- (B-1) and 2-(N-ethyl 4-pyridinium)vinyl- (B-2), and a neutral group, acroleinyl- (B-3); the charged species resemble cyanine (or styryl) dye motifs whereas the neutral unit resembles a merocyanine dye motif. The three Bacteriochlorins are examined by static and time-resolved absorption and emission spectroscopy and density functional theoretical calculations. B-1 and B-2 have Qy absorption bathochromically shifted well into the NIR region (822 and 852 nm), farther than B-3 (793 nm) and other 3,13-disubstituted Bacteriochlorins studied previously. B-1 and B-2 have broad Qy absorption and fluorescence features with large peak separation (Stokes shift), low fluorescence yields, and shortened S1 (Qy ) excited-state lifetimes (~700 ps and ~100 ps). More typical spectra and S1 lifetime (~2.3 ns) are found for B-3. The combined photophysical and molecular-orbital characteristics suggest the altered spectra and enhanced nonradiative S1 decay of B-1 and B-2 derive from excited-state configurations in which electron density is shifted between the macrocycle and the substituents.
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extending the short and long wavelength limits of bacteriochlorin near infrared absorption via dioxo and bisimide functionalization
Journal of Physical Chemistry B, 2015Co-Authors: Pothiappan Vairaprakash, Dariusz M Niedzwiedzki, Christine Kirmaier, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Tuba Sahin, Michael Krayer, Alfred Wang, Jonathan S LindseyAbstract:Six new Bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin–bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin–bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin–monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin–monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer si...
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Extending the Short and Long Wavelength Limits of Bacteriochlorin Near-Infrared Absorption via Dioxo- and Bisimide-Functionalization
2015Co-Authors: Pothiappan Vairaprakash, Dariusz M Niedzwiedzki, Christine Kirmaier, Masahiko Taniguchi, Eunkyung Yang, James R Diers, Tuba Sahin, Michael Krayer, Alfred Wang, Jonathan S LindseyAbstract:Six new Bacteriochlorins expanding the range of the strong near-infrared (NIR) absorption (Qy band) to both shorter and longer wavelengths (∼690 to ∼900 nm) have been synthesized and characterized. The architectures include bacteriochlorin–bisimides that have six-membered imide rings spanning the 3,5- and 13,15-macrocycle positions or five-membered imide rings spanning the β-pyrrolic 2,3- and 12,13-positions. Both bisimide types absorb at significantly longer wavelength than the bacteriochlorin precursors (no fused rings), whereas oxo-groups at the 7- or 7,17-positions shift the Qy band to a new short wavelength limit. Surprisingly, bacteriochlorin–bisimides with five-membered β-pyrrolic-centered imide rings have a Qy band closer to that of six-membered bacteriochlorin–monoimides. However, the five-membered bisimides (versus the six-membered bacteriochlorin–monoimides) have significantly enhanced absorption intensity that is paralleled by an ∼2-fold higher fluorescence yield (∼0.16 vs ∼0.07) and longer singlet excited-state lifetime (∼4 ns vs ∼2 ns). The photophysical enhancements derive in part from mixing of the lowest unoccupied frontier molecular orbitals of the five-membered imide ring with those of the bacteriochlorin framework. In general, all of the new Bacteriochlorins have excited-state lifetimes (1–4 ns) that are sufficiently long for use in molecular-based systems for photochemical applications
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stable synthetic mono substituted cationic Bacteriochlorins mediate selective broad spectrum photoinactivation of drug resistant pathogens at nanomolar concentrations
Journal of Photochemistry and Photobiology B-biology, 2014Co-Authors: Liyi Huang, Jonathan S Lindsey, Dewey Holten, Michael Krayer, Yingying Huang, Michael R Hamblin, John G S RoubilAbstract:Abstract Three stable synthetic mono-substituted cationic Bacteriochlorins (BC37, BC38 and BC39) were recently reported to show exceptional activity (low nanomolar) in mediating photodynamic killing of human cancer cells after a 24 h incubation upon excitation with near-infrared light (730 nm). The presence of cationic quaternary ammonium groups in each compound suggested likely activity as antimicrobial photosensitizers. Herein this hypothesis was tested against a panel of pathogenic microorganisms that have all recently drawn attention due to increased drug-resistance (Gram-positive bacteria, Staphylococcus aureus and Enterococcus faecalis; Gram-negative bacteria, Escherichia coli and Acinetobacter baumannii; and fungal yeasts, Candida albicans and Cryptococcus neoformans). All three Bacteriochlorins were highly effective against both Gram-positive species (>6 logs of eradication at ⩽200 nM and 10 J/cm2). The dicationic bacteriochlorin (BC38) was best against the Gram-negative species (>6 logs at 1–2 μM) whereas the lipophilic monocationic bacteriochlorin (BC39) was best against the fungi (>6 logs at 1 μM). The Bacteriochlorins produced substantial singlet oxygen (and apparently less Type-1 reactive-oxygen species such as hydroxyl radical) as judged by activation of fluorescent probes and comparison with 1H-phenalen-1-one-2-sulfonic acid; the order of activity was BC37 > BC38 > BC39. A short incubation time (30 min) resulted in selectivity for microbial cells over HeLa human cells. The highly active photodynamic inactivation of microbial cells may stem from the amphiphilic and cationic features of the Bacteriochlorins.
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photophysical properties and electronic structure of bacteriochlorin chalcones with extended near infrared absorption
Photochemistry and Photobiology, 2013Co-Authors: Eunkyung Yang, Dariusz M Niedzwiedzki, Christine Kirmaier, David F Bocian, Jonathan S Lindsey, James R Diers, Michael Krayer, Christian Ruzie, Dewey HoltenAbstract:Synthetic Bacteriochlorins enable systematic tailoring of substituents about the bacteriochlorin chromophore and thereby provide insights concerning the native bacteriochlorophylls of bacterial photosynthesis. Nine free-base Bacteriochlorins (eight prepared previously and one prepared here) have been examined that bear diverse substituents at the 13- or 3,13-positions. The substituents include chalcone (3-phenylprop-2-en-1-onyl) derivatives with groups attached to the phenyl moiety, a "reverse chalcone" (3-phenyl-3-oxo-1-enyl), and extended chalcones (5-phenylpenta-2,4-dien-1-onyl, retinylidenonyl). The spectral and photophysical properties (τs, Φf, Φ(ic), Φ(isc), τT, k(f), k(ic), k(isc)) of the Bacteriochlorins have been characterized. The Bacteriochlorins absorb strongly in the 780-800 nm region and have fluorescence quantum yields (Φf) in the range 0.05-0.11 in toluene and dimethylsulfoxide. Light-induced electron promotions between orbitals with predominantly substituent or macrocycle character or both may give rise to some net macrocycle ↔ substituent charge-transfer character in the lowest and higher singlet excited states as indicated by density functional theory (DFT) and time-dependent DFT calculations. Such calculations indicated significant participation of molecular orbitals beyond those (HOMO - 1 to LUMO + 1) in the Gouterman four-orbital model. Taken together, the studies provide insight into the fundamental properties of Bacteriochlorins and illustrate designs for tuning the spectral and photophysical features of these near-infrared-absorbing tetrapyrrole chromophores.
