Synthesis, X-ray crystal structure, thermal and solution studies of a centrosymmetric metal–organic polymer based on proton transfer methodology

Abstract

A 3-D metal-organic coordination polymer based on pyrazine-2,3-dicarboxylic acid (pzdcH 2 ) formulated as {[Mn(pzdc)(H 2 O) 2 ] Á 2H 2 O} n (1), was obtained by the treatment of MnCl 2 Á 6H 2 O with pzdcH 2 , 8-hydroxy quinoline (8-HQ), and 2-amino-4-methyl pyridine (ampy). In this study, we describe the synthesis, elemental analysis, IR spectroscopy, TG analysis, and single X-ray diffraction. The X-ray single crystal structure reveals that the chemical environment around each Mn(II) is a distorted octahedral by participating one nitrogen, five oxygens from three (pzdc) 2À and two water molecules, O 5 MnN. The centrosymmetric 1-D ladder-like structure of 1 is bridged by oxygens of (pzdc) 2À, and Mn-pzdc-Mn bonds are the rungs for our ladder structure. In the crystal structure, intermolecular O-H Á Á Á O hydrogen bonds result in the formation of a supramolecular structure, effective for the stabilization of the structure. The thermal decomposition of 1 indicates that it is quite thermally stable. The protonation constants of ampy, 8-HQ and pzdcH 2 as the building blocks of proton transfer systems including pzdcH 2 -ampy and pzdcH 2 -8-HQ and the corresponding stability constants of these systems were determined by potentiometric study. The stoichiometry and stability constants of complexes of pzdcH 2 -ampy and pzdcH 2 -8-HQ with Mn 2þ were investigated by this method in aqueous solution. The results obtained from solution study are comparable with the solid state results.

The first mixed-ligand coordination compound involving 8-aminoquinoline and pyridine-2,6-dicarboxylate: synthesis, X-ray crystal structure, and DFT studies

“…The uncoordinated water molecules act as a gluing factor to connect discrete cationic and anionic complexes, generating 1D chains with the ring having the graph-set notation R 4 4 (16) and R 2 2 (14) along the crystallographic b axis. Additionally, infinite 1D chains join via N−H···O hydrogen bonds between amino and carboxylate groups creating a R 7 7 (28) graph set along the crystallographic c axis (see figure 3).…”

“…Prior work indicates that polycarboxylate and neutral multidentate N- there is a large number of aromatic polycarboxylic acids which have been used as modular precursors for construction of coordination networks, in particular H 2 py-2,6-dc with 900 coordination compounds is a frequently used precursor. In this context, our research group has focused on preparing supramolecular crystalline coordination compounds based on various dicarboxylic acids such as pyridine-2,3-dicarboxylic acid [15], pyrazine-2,3-dicarboxylic acid [16], pyridine-2,5-dicarboxylic acid [7] and especially pyridine-2,6-dicarboxylic acid [17]. As a ligand, (py-2,6-dc) 2-is a symmetrical chelating ligand which can complete the metal coordination sphere and compensate charge [17] as well as providing non-covalent contacts such as hydrogen bonding and aromatic stacking for controlling growth of supramolecular networks.…”

Syntheses, crystal, molecular structures, and solution studies of Cu(II), Co(II), and Zn(II) coordination compounds containing pyridine-2,6-dicarboxylic acid and 1,4-pyrazine-2,3-dicarboxylic acid: comparative computational studies of Cu(II) and Zn(II) complexes

“…Functional groups are widely employed to construct crystalline edifice [14,15]. In this work, a systematic study was employed for proton-transfer process from carboxylic acids to amines [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. PydcH 2 and pyzdcH 2 were used as ligands in designing coordination compounds with various dimensionalities and inducing selfassembly processes [30][31][32][33][34][35][36][37][38][39][40][41][42].…”

“…As valuable characters are: (a) heterocyclic acid with two carboxyl groups, (b) form hydrogen bonding and aromatic-aromatic stacking interactions, (c) contain N-or O-donor atoms, these leads to new structures with diverse dimensional. Previously, the syntheses and structural characterization of some coordination compounds via proton-transfer methodology were described [16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Herein, the syntheses and potentiometric studies of three new Cu(II), Co(II), and Zn(II) coordination compounds involving abovementioned dicarboxylic acids as proton donors, and Acr and 2a-4mpy heterocyclic amines as proton acceptors are reported.…”

Synthesis and crystal structure of trans-[Ni(pyzdcH)M₂(H₂O) ₂] based on pyrazine-2,3-dicarboxylic acid

“…So, organic ligands and aromatic molecules have been studied extensively in the crystal structure to assemble supramolecular network organized by coordination bonds, hydrogen bonds and π-π stacking interaction [5]. As one of these ligands, the dicarboxylate ligand, pyzdcH 2 has drawn extensive attentions [6][7][8][9][10][11][12][13][14][15]. Metal pyrazine dicarboxylate complexes can construct versatile structural motifs, which generate various supramolecular architectures with interesting properties.…”