A brief review on structural concepts of novel supramolecular proton transfer compounds and their metal complexes

Abstract

Our research group has been interested in synthesis of proton transfer compounds as new supramolecular synthons for the onepot preparation of self-assembled transition metal complex-organo-networks since 2000. We have focused on the proton delivery from acids, which are considered as suitable proton donors, to amines as proton acceptors. The results were production of several proton transfer ion pairs possessing some remaining donor sites applied for coordination to metallic centers in preparation of metal-organic structures. Some of the complexes showed contributions of both cationic and anionic fragments of the starting ion pair, while some others contained only one of these species as ligand. Much of the investigations on reviewed compounds focused on the concept of supramolecular systems, co-crystallization, stereochemically active lone pairs, coordination polyhedron and mainly on various interactions involve including van der Waals, ion pairing, hydrogen bondings, face to face -stackings and edge to face C-H··· , C-O··· , N-H··· , S-O··· , Ti··· and Hg-Cl··· interactions. The mentioned interactions are the most commonly used strategies in the extension of supramolecular structures.

Synthesis and characterization of some metal complexes of a proton transfer salt, and their inhibition studies on carbonic anhydrase isozymes and the evaluation of the results by statistical analysis

“…Introduction 2,6-Pyridinedicarboxylic acid (or dipicolinic acid, H 2 DPC) is commonly used as an acid in proton transfer systems 1 . Continuing the path to synthesize water soluble proton transfer compounds, our group has focused on forming ion pairs between H 2 DPC and various organic bases, such as 2-aminobenzothiazole 2 , 2-amino-6-methylbenzothiazole 3 , 2-(piperazin-1-yl)ethanol 4 , 2-amino-4-methylpyridine 5 .…”

“…Continuing the path to synthesize water soluble proton transfer compounds, our group has focused on forming ion pairs between H 2 DPC and various organic bases, such as 2-aminobenzothiazole 2 , 2-amino-6-methylbenzothiazole 3 , 2-(piperazin-1-yl)ethanol 4 , 2-amino-4-methylpyridine 5 . The interest of metal complexes for H 2 DPC and its deprotonated forms, HDPC À and DPC 2À , stems from their interesting structural features with various coordination modes 1 , stabilization of unusual oxidation states 6 and insulinmimetic effects 7,8 . Benzothiazoles and their simple metal complexes are well known for their biological activities 2,3, 9,10 .…”

“…The mixed ligand metal complexes of these compounds have shown better biological activities than the simple ones [2][3][4] . In order to prepare the mixed ligand complexes, two types of ligands, generally acids and bases, are brought together before coordination to the metal ion [1][2][3][4][5]16,17 . In this study, a novel proton transfer compound (HMeOABT) Furthermore, we have investigated the potential use of these compounds as new inhibitors of human carbonic anhydrase (hCA I and hCA II) isozymes in the treatment of glaucoma, which is a group of diseases characterized by the gradual loss of visual field due to an elevation in intraocular pressure (IOP) 18,19 .…”

Crystal structure of 2,2′-(1,2-ethanediyl)bis(1H-benzimidazolium) bis(dihydrogen benzene-1,3,5-tricarboxylate), [C16H16N4][C9H5O6]2

“…Recently, the benzimidazole ring system is found in clinically approved anthelmintics, antiulcers, antivirals, and antihistamines [2]. A number of cases were reported in which aproton transferred from acarboxylic acid to an amine formed novel proton transfer compounds [3]. In this work, we report anew proton transfer compound obtained from benzene-1,3,5-tricarboxylic acid as aproton donor and bis-benzimidazoles as an acceptor.…”

Crystal structure of 4,4'-bipyridinium bis(pyridine-2,6- dicarboxylato)mercurate(II) — diaquabis(6-carboxypyridine- 2-carboxylato)mercury(II)— water (2:1:12), [C10H10N2]2[Hg(C7H3NO4)2]2 · Hg(H2O)2(C7H4NO4)2 · 12H2O

“…In recent years in astrategy towards rational design of coordination compounds, based on proton transfer mechanism, we have used various dicarboxylic acids and amines derivatives [1]. Pyridine-2,6-dicarboxylic acid (pydcH 2 )w hich incorporated in many biologically important systems, is subject of many studies in view of experimentally or/and theoretically [2][3][4].…”