Homo- or Heterosynthon? A Crystallographic Study on a Series of New Cocrystals Derived from Pyrazinecarboxamide and Various Carboxylic Acids Equipped with Additional Hydrogen Bonding Sites

2012 ◽  
Vol 12 (5) ◽  
pp. 2533-2542 ◽  
Author(s):  
Tapas Kumar Adalder ◽  
Ravish Sankolli ◽  
Parthasarathi Dastidar
Keyword(s):  
Hydrogen Bonding ◽  
Carboxylic Acids ◽  
Crystallographic Study ◽  
Additional Hydrogen

scholarly journals Recent Progress in Hydrogen-Bonded π-Conjugated Systems Displaying J-Type Aggregates

2020 ◽  
Vol 02 (01) ◽  
pp. 047-063 ◽  
Author(s):  
Nelson Ricardo Ávila-Rovelo ◽  
Amparo Ruiz-Carretero
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Noncovalent Interactions ◽  
Functional Materials ◽  
Organic Electronic Devices ◽  
Conjugated Systems ◽  
Hydrogen Bonding Interactions ◽  
Different Types ◽  
J Aggregates ◽  
Additional Hydrogen

Supramolecular approaches are of great interest in the design of functional materials. The types of aggregates arising from different noncovalent interactions endow materials with intriguing properties. In this sense, J-type aggregates are very attractive due to their unique optical properties and capacity to transport excitons. These features make them great candidates in the design of materials for organic electronic devices. Furthermore, the incorporation of additional hydrogen-bonding functionalities provides J-aggregates with superior directionality and connection among the different π-conjugated cores. The control over the formation of H-bonds to achieve functional aggregates is therefore a promising strategy towards controlled structures with specific functions.This review outlines the most relevant and recent works of π-conjugated systems exhibiting J-type aggregates resulting from hydrogen-bonding interactions. Different types of hydrogen-bonding functionalities will be discussed together with their roles in the aggregate properties, their impact in the optoelectronic properties, the self-assembly mechanisms, and their applications in organic electronics.

scholarly journals A substrate selected by phage display exhibits enhanced side-chain hydrogen bonding to HIV-1 protease

2018 ◽  
Vol 74 (7) ◽  
pp. 690-694 ◽  
Author(s):  
Ian W. Windsor ◽  
Ronald T. Raines
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Molecular Recognition ◽  
Hydrogen Bonds ◽  
Phage Display ◽  
Directed Evolution ◽  
Side Chain ◽  
Endogenous Substrates ◽  
Hiv 1 ◽  
Additional Hydrogen

Crystal structures of inactive variants of HIV-1 protease bound to peptides have revealed how the enzyme recognizes its endogenous substrates. The best of the known substrates is, however, a nonnatural substrate that was identified by directed evolution. The crystal structure of the complex between this substrate and the D25N variant of the protease is reported at a resolution of 1.1 Å. The structure has several unprecedented features, especially the formation of additional hydrogen bonds between the enzyme and the substrate. This work expands the understanding of molecular recognition by HIV-1 protease and informs the design of new substrates and inhibitors.

scholarly journals Crystal structure of pentakis(ethylenediamine-κ2N,N′)lanthanum(III) trichloride–ethylenediamine–dichloromethane (1/1/1)

2014 ◽  
Vol 70 (11) ◽  
pp. 424-426 ◽  
Author(s):  
Hope T. Sartain ◽  
Richard J. Staples ◽  
Shannon M. Biros
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonding ◽  
Hydrogen Bonds ◽  
Electron Density ◽  
Inversion Center ◽  
Asymmetric Unit ◽  
Acta Cryst ◽  
Bypass Procedure ◽  
Hydrogen Bonding Network ◽  
Additional Hydrogen

We report here the crystal structure of a ten-coordinate lanthanum(III) metal coordinated by five bidentate ethylenediamine ligands, [La(C2H8N2)5]Cl3·C2H8N2·CH2Cl2. One free ethylenediamine molecule and three Cl−anions are also located in the asymmetric unit. The overall structure is held together by an extensive hydrogen-bonding network between the Cl−anions and the NH groups on the metal-bound ethylenediamine ligands. The free ethylenediamine molecule is held in an ordered position by additional hydrogen bonds involving both the chlorides and –NH groups on the metal-bound ligands. One highly disordered molecule of dichloromethane is located on an inversion center; however, all attempts to model this disorder were unsuccessful. The electron density in this space was removed using the BYPASS procedure [van der Sluis & Spek (1990).Acta Cryst.A46, 194–201].

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