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Gautam R Desiraju - One of the best experts on this subject based on the ideXlab platform.
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using water as a design element in crystal engineering host guest Compounds of hydrated 3 5 dihydroxybenzoic acid
Crystal Growth & Design, 2010Co-Authors: Sunil Varughese, Gautam R DesirajuAbstract:Thirteen host−guest Compounds of 3,5-dihydroxybenzoic acid (DHBA) have been structurally characterized. Water molecules occupy the peripheries of a hexagonal void, created with DHBA molecules, and act as “hooks” to connect the guest molecules with the host-framework via hydrogen bonding. The “water hook” is an OH group acting as a donor. Consequently, the guest molecules were chosen so that they contain good hydrogen bond acceptor functionalities. A number of multicomponent hydrates were isolated with stoichiometries (DHBA)x(H2O)y(guest)z. Of these, Compounds with the following as guests were obtained as crystals that were good enough for single crystal work: ethyl acetate (EtOAc), diethyl oxalate, dimethyl oxalate, di(n-propyl) oxalate, diethyl malonate, diethyl succinate, chloroacetonitrile, N,N-dimethyl formamide (DMF), acetone, dimethyl sulfoxide (DMSO), 1-propanol, and 2-butanol. From 2-butanol, a hemihydrate, (DHBA)2(H2O), was also obtained concomitantly. Further to guest stabilization, water acts a...
Sunil Varughese - One of the best experts on this subject based on the ideXlab platform.
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using water as a design element in crystal engineering host guest Compounds of hydrated 3 5 dihydroxybenzoic acid
Crystal Growth & Design, 2010Co-Authors: Sunil Varughese, Gautam R DesirajuAbstract:Thirteen host−guest Compounds of 3,5-dihydroxybenzoic acid (DHBA) have been structurally characterized. Water molecules occupy the peripheries of a hexagonal void, created with DHBA molecules, and act as “hooks” to connect the guest molecules with the host-framework via hydrogen bonding. The “water hook” is an OH group acting as a donor. Consequently, the guest molecules were chosen so that they contain good hydrogen bond acceptor functionalities. A number of multicomponent hydrates were isolated with stoichiometries (DHBA)x(H2O)y(guest)z. Of these, Compounds with the following as guests were obtained as crystals that were good enough for single crystal work: ethyl acetate (EtOAc), diethyl oxalate, dimethyl oxalate, di(n-propyl) oxalate, diethyl malonate, diethyl succinate, chloroacetonitrile, N,N-dimethyl formamide (DMF), acetone, dimethyl sulfoxide (DMSO), 1-propanol, and 2-butanol. From 2-butanol, a hemihydrate, (DHBA)2(H2O), was also obtained concomitantly. Further to guest stabilization, water acts a...
Klaus Kern - One of the best experts on this subject based on the ideXlab platform.
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grafting crown ether alkali host guest complexes at surfaces by electrospray ion beam deposition
Journal of Physical Chemistry C, 2010Co-Authors: Nicha Thontasen, Giacomo Levita, N Malinowski, Zhitao Deng, Stephan Rauschenbach, Klaus KernAbstract:The functionalization of surfaces with host−guest Compounds is promising for many applications, yet often limited by constraints such as the volatility of the functional compound or the lack of binding to the surface. We use electrospray ion beam deposition (ES-IBD) on surfaces in ultrahigh vacuum as a novel approach to modify an atomically defined copper surface with preformed dibenzo-24-crown-8-alkali complexes, in which the central ion (H+, Na+, or Cs+) can be exchanged in the electrospray solution. In situ scanning tunneling microscopy maps the single alkali ion complexes as an oval protrusion with a four-lobe submolecular structure immobilized at the surface. Density functional theory calculations confirm that the crown ether is bound to the surface via the central alkali ion within its cavity, indicating that the properties of the molecular complex are retained after deposition.
Luigi R Nassimbeni - One of the best experts on this subject based on the ideXlab platform.
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Guest Exchange in Halogenated Host–Guest Compounds: Structures and Kinetics
2016Co-Authors: Francoise Amombo M Noa, Susan A Bourne, Luigi R NassimbeniAbstract:The host Compounds tetrakis(4-bromophenyl) ethylene, H1, and its iodo-analogue (H2) form inclusion Compounds with the guests 1,2-dichloroethane (DCE), methyl iodide (MeI), benzene (BEN), and piperidine (PIP). The structures of the host–guest Compounds have been elucidated and a series of exchange experiments on these Compounds were performed by exposing their single crystals to the vapors of different guests. The kinetics of the exchange was monitored by NMR spectroscopy, and the reactions were interrupted and the structures of the inclusion Compounds containing both the incoming and outgoing guests were solved. In the case of 1.5H1·DCE exchanged with MeI, the intermediate structure yields a unit cell which has quadrupled in volume and shows both DCE and MeI in distinct, different locations. In the case of BEN being exchanged with PIP, the guests occupy the same site, and the mechanism is one of isomorphous replacement
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Hydrogen Bonding versus Halogen Bonding in Host–Guest Compounds
2016Co-Authors: Francoise Amombo M Noa, Susan A Bourne, Edwin Weber, Luigi R NassimbeniAbstract:The similarity and differences of the three host Compounds H1 = 9,9′-(biphenyl-2,2′-diyl)difluoren-9-ol, H2 = 2,2′,7,7′-tetrabromo-9,9′-(biphenyl-2,2′-diyl)difluoren-9-ol, and H3 = 2,2′,7,7′-tetra-tert-butyl-9,9′-(1,4-phenylene)difluoren-9-ol which form inclusion Compounds with 3-bromopyridine and its chloro-analogue guest are compared with respect to hydrogen bonding and halogen bonding. In all cases the hydrogen bonding motif (Host)O–H···O(Host)–H···N(Guest) predominates while the halogen···halogen interactions are of secondary importance in the packing of the structures. The structural data are supported by thermal analysis, Hirshfeld surface analysis, and IR spectroscopy
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halogen bonding in host guest Compounds structures and kinetics of enclathration and desolvation
Acta Crystallographica Section A, 2015Co-Authors: Francoise Amombo M Noa, Susan A Bourne, Luigi R NassimbeniAbstract:The host Compounds tetrakis(4-bromophenyl) ethylene and its iodo-analogue form inclusion Compounds with a series of chloro- and iodo-methanes. Their structures have been elucidated, and their nonbonded halogen···halogen contacts have been analyzed and classified. Their kinetics of desolvation have been studied, and the concomitant activation energies have been established. Five of the clathrates are isostructural and display similar activation energies of desolvation, thus correlating structure and function. The velocity of the enclathration for the solid host–methyl iodide vapor reactions and associated rate law have been established.
Nicha Thontasen - One of the best experts on this subject based on the ideXlab platform.
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grafting crown ether alkali host guest complexes at surfaces by electrospray ion beam deposition
Journal of Physical Chemistry C, 2010Co-Authors: Nicha Thontasen, Giacomo Levita, N Malinowski, Zhitao Deng, Stephan Rauschenbach, Klaus KernAbstract:The functionalization of surfaces with host−guest Compounds is promising for many applications, yet often limited by constraints such as the volatility of the functional compound or the lack of binding to the surface. We use electrospray ion beam deposition (ES-IBD) on surfaces in ultrahigh vacuum as a novel approach to modify an atomically defined copper surface with preformed dibenzo-24-crown-8-alkali complexes, in which the central ion (H+, Na+, or Cs+) can be exchanged in the electrospray solution. In situ scanning tunneling microscopy maps the single alkali ion complexes as an oval protrusion with a four-lobe submolecular structure immobilized at the surface. Density functional theory calculations confirm that the crown ether is bound to the surface via the central alkali ion within its cavity, indicating that the properties of the molecular complex are retained after deposition.