Influence of structural variation of salamo‐based ligand on supramolecular architectures, Hirshfeld analyses, and fluorescence properties of new tetranuclear Ni^II complexes

Abstract

Two new tetranuclear Ni II complexes, [Ni 4 (L 1) 2 (N 3) 4 (MeOH) 2 ]ÁCH 3 COCH 3 (1) and [Ni 4 (L 2) 2 (N 3) 4 (MeOH) 2 ]Á4CH 3 COCH 3 (2), were synthesized using NiCl 2 Á6H 2 O, NaN 3 , and asymmetric salamo-based ligands H 2 L 1 and H 2 L 2 , respectively. The structural characterization was made by elemental analyses, infrared (IR) and ultraviolet-visible (UV-vis) spectra, and X-ray diffraction analyses. The results of X-ray diffraction analyses show that the Ni II atoms in complexes 1 and 2 are distorted octahedral geometries. Interestingly, the degree of distortion of the ligands in complexes 1 and 2 is different, which indicates that the interaction of Ni II ions on different ligands is different. Meanwhile, the investigation of molecular packing by employing the Hirshfeld surface analysis exhibits that the percentages of C-H/H-C, O-H/H-O, and H-H/H-H contacts of the complex 1 (or 2) are calculated to be 17.7%, 7.9%, and 53.7% (or 18.8%, 13.8%, and 52.5%), respectively, where the H-H/H-H contacts have the characteristics of strong contacts whereas the O-H/H-O hydrogen bonds are considerably weak, and the studies on fluorescence properties further confirm the Ni II atoms have different binding abilities to the different ligands.

Construction of novel hexanuclear Co(II) and dinuclear Ni(II) bis(salamo)‐type complexes

“…The original hydrogen bonding interactions of the ligand have been destroyed, which leads to the change of UV-Vis spectra. [50] In addition, the crystal structures of complexes 1 and 2 are consistent with the Job curve in Figure S2; these results demonstrate further the stoichiometric ratios of complexes 1 and 2.…”

“…[49] The characteristic frequency of C═N stretching vibration of the free ligand H 4 L was observed at about 1607 cm À1 ; this band is shifted by 19 and 10 cm À1 in the low-wavenumber direction in complexes 1 and 2, showing that the Co(II) and Ni(II) atoms have bonded with N atoms of the ligand. [50] As reported, the Ar O stretching frequency as a strong band often appears in the 1213-1263 cm À1 range. [51] The Ar O stretching vibration of the ligand H 4 L was found at about 1245 cm À1 , but those of complexes 1 and 2 are 1234 and 1239 cm À1 , respectively.…”

Self-assembling of three rare structurally various homomultinuclear CuII complexes derived from a bis(salamo)-based multioxime ligand

“…In recent years, a new type of the salenbased analog, salamo-based ligands [R-CH N-O-(CH 2 ) n -O-N CH-R] were developed and many functional ligands have been designed and synthesized. Due to the structural characteristics of the salamo-based ligands, the electronegativity of the oxygen atoms can significantly affect the electron density distribution of the N 2 O 2 cavities and control the reversible reaction of the imine bond (Pan et al, 2020a;Wei et al, 2020;Mu et al, 2020;Wang et al, 2020a,b;Zhang et al, 2020a,d;Liu et al, 2020bLiu et al, ,a, 2019aKang et al, 2019;Zhang et al, 2019;Bian et al, 2021;Xu et al, 2021;Cui et al, 2021). Compared with the salen-based, salamo-based ligands and their complexes have better flexibilities and solubilities, as well as stronger stabilities (Wei et al, 2019;An et al, 2019;Liu et al, 2019a), with the continuous deepening and expansion of their researches, a variety of 3d (Pan et al, 2020b;Yu et al, 2020;Xu et al, 2020b), 3d-s , 3d-4f (Zhang et al, 2020a,d;An et al, 2020;Zhao et al, 2019;Li et al, 2019;Cui et al, 2019;Xu et al, 2019) homoand hetero-metal multinuclear complexes and coordination polymers have been developed by spontaneously forming coordination bonds of metal atoms and the multidentate chelate ligands.…”

An investigation of structure, Hirshfeld surface, and fluorescence properties of two dinuclear Ni (II) and Zn (II) salamo‐type complexes

“…[22][23][24][25][26][27][28][29][30] Due to the electronegativity of the oxygen atoms, which can significantly affect the reversible reaction of the imine bond, salomo-based compounds with specific functions [31][32][33][34][35][36][37] and novel structures were synthesized. [38][39][40][41][42][43][44][45] With the continuous deepening and expansion of their research, a lot of 3d, [46][47][48][49][50] 3d-s, [51] 3d-4f [52][53][54][55] complexes have been synthesized by coordination-driven self-assembling, at the same time, the fast and efficient chemical probes have also been developed. [56][57][58][59] The molecular and/or ionic components contained similar structures are relatively rare situation, meanwhile, the τ 5 parameter is the most widely used measure of the geometry of five-coordinate transition metal complexes, remarkably, there are few such examples of τ 5 being very close to 0.500.…”

“…[ 22–30 ] Due to the electronegativity of the oxygen atoms, which can significantly affect the reversible reaction of the imine bond, salomo‐based compounds with specific functions [ 31–37 ] and novel structures were synthesized. [ 38–45 ] With the continuous deepening and expansion of their research, a lot of 3d, [ 46–50 ] 3d‐s, [ 51 ] 3d‐4f [ 52–55 ] complexes have been synthesized by coordination‐driven self‐assembling, at the same time, the fast and efficient chemical probes have also been developed. [ 56–59 ]…”