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Azines (2,3-diaza-1,3-butadienes): structure, electronic structure, tautomerism, and their applications in organic synthesis, medicinal chemistry and materials chemistry.

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Organophosphorus pesticides (OPPs) are generally utilized for the protection of crops from pests. Because the use of OPPs in various agricultural operations has expanded dramatically, precise monitoring of their concentration...

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In this report, novel unsymmetrical azines have been designed and synthesised by using one pot approach. Further, they were evaluated as quorum sensing inhibitors.

Coordination chemistry of bonds between main group elements and electron donating ligands as in L→E (where E is electron acceptor centre like C 0 , Si 0 , N 1 , P 1 , As 1 , B 1 and L is an electron donating N-heterocyclic carbene) has been recently gaining attention. Many important drugs have nitrogen atom as an electron acceptor center and can be represented by two general formulae: (L→N←L) ⊕ and L→N-R. Divalent N 1 compounds possess two lone pairs at central nitrogen and low nucleophilicity associated with them is found to be of importance. In this article, electronic structure analysis of drug molecules like picloxydine, chlorhexidine, and moroxydine was performed at B3LYP/6-311++G(d,p) level of theory. Evaluation of electron localization function (ELF), molecular orbitals, charge density, nucleophilicity, proton affinity and complexation energy estimation confirms the presence of coordination bonds (L→N←L) ⊕ in the above mentioned drug molecules in their cationic state. Further, electronic structure analysis of drugs like clonidine, apraclonidine, brimonidine and xylazine indicated the presence of electronic structure similar to L→N-R systems.

Guanylhydrazones have been known for a long time and have wide applications in organic synthesis, medicinal chemistry, and material science; however, little attention has been paid toward their electronic and structural properties. Quantum chemical analysis on several therapeutically important guanylhydrazones indicated that all of them prefer the azine tautomeric state (by about 3-12 kcal/mol). A set of simple and conjugated azines were designed using quantum chemical methods, whose tautomeric preference toward the azine tautomer is in the range of 3-8 kcal/mol. Twenty new azines were synthesized and isolated in their neutral state. Variable temperature NMR study suggests existence of the azine tautomer even at higher temperatures with no traces of the hydrazone tautomer. The crystal structures of two representative compounds confirmed that the title compounds prefer to exist in their azine tautomeric form.