Synthesis, Crystal Structures and Fluorescent Properties of Two 2,2′‐Biquinoline‐4,4′‐dicarboxylate‐based Cadmium(II) and Cobalt(II) Complexes

Abstract

Two metal‐organic coordination polymers with one‐dimensional infinite chain motif, [Cd(bqdc)(phen)2]n (1) and [Co(bqdc)(phen)(H2O)2]n (2) (H2bqdc = 2,2′‐biquinoline‐4,4′‐dicarboxylic acid, phen = 1,10‐phenanthroline), have been synthesized under similar solv/hydrothermal conditions and fully structural characterized by elemental analysis, IR, and single‐crystal X‐ray crystallography. Their thermal stability and photoluminescence properties were further investigated by TG‐DTA and fluorescence spectra. In both complexes, the adjacent metal ions (CdII for 1 and CoII for 2) are linked together by dicarboxylate groups of bqdc dianions in chelating bidentate and monodentate modes, respectively, generating a zigzag chain for 1 and linear chain for 2. The relatively higher thermal stability up to 324 °C for 1 and strong fluorescence emissions jointly suggest that they are good candidates for luminescent materials.

Catalytic C–H Bond Activation and Knoevenagel Condensation Using Pyridine-2,3-Dicarboxylate-Based Metal–Organic Frameworks

“… Furthermore, the presence of the strong peaks at 1667 and 1587 cm –1 may be associated with the characteristic of asymmetric stretching (ν as ) vibrations due to the −COO – group, whereas the peaks observed at 1442 and 1394 cm –1 are attributed to symmetric stretching (ν s ) vibration of the −COO – group. Relatively larger separations >200 cm –1 between ν as (COO – ) and ν s (COO – ) indicate the monodentate coordination mode of the carboxylate group, whereas smaller separation <200 cm –1 suggests the chelating bidentate coordination mode of the carboxylate group. − The presence of the corresponding Δν value >200 and <200 cm –1 in the same spectrum indicates both bidentate and monodentate −COO – coordination mode in the 2,3-pdca ligand which has further been authenticated by X-ray single-crystal analyses (vide supra). The other important absorption bands that appear in the IR spectrum of 1 are νC–H (2980 cm –1 ) and νCC (1464 cm –1 ) (Figure S19.1).…”

“…CP 3 shows vibrations at 3441 cm –1 (νH 2 O), 1583 cm –1 (ν as –COO – ), and 1369 cm –1 (ν as –COO – ) (Figure S19.3). ,,, On the other hand, the FT-IR spectrum of 4 displayed a vibration at 3238 cm –1 which may be attributed to the −N–H stretching band of quaternary amine (CH 3 ) 2 NH 2 + . Furthermore, characteristic ν as and ν s bands of −COO – groups of 2,3-pdca appear at 1633 and 1592 cm –1 and at 1425 and 1382 cm –1 (Figure S19.4), having Δν value >200 cm –1 which indicates that the carboxylates of 2,3-pdca ligand are linked with Cu­(II)/K­(I) adopting bidentate and/or bridged bidentate coordination modes .…”

“…129 Likewise, 2 exhibited vibration at 3517 cm −1 owing to the coordinated water molecules along with characteristic vibrations associated with ν as and ν s −COO − groups at 1661 and 1555 cm −1 and at 1441 and 1379 cm −1 , respectively (Figure S19.2). 124,125 Weak vibrations present in the range 425−460 cm −1 may be attributed to Cd−N and Cd− O stretching vibrations. 129 CP 3 shows vibrations at 3441 cm −1 (νH 2 O), 1583 cm −1 (ν as −COO − ), and 1369 cm −1 (ν as − COO − ) (Figure S19.3).…”

Synthesis, crystal structure, and fluorescence properties of a novel coordination polymer [Zn(L)(4,4′-bipyridine)(H2O)] n · (H2O)4

“…The weak δ(C=O) absorption band at 1719 cm -1 exhibits full carboxyl group coordination modes for the metal ions [26]. The δ(C-N) peak displayed at 1213 cm -1 and the other strong absorption peak observed at 1161-1582 cm -1 can be attributed to stretching of the aro matic ring [27,28].…”