Polymer Chemistry
·
2014
·Vol. 5
·期 12
·3838-3846
·
IF 5.368
Yonghang Xu,Min Xiao,Shuanjin Wang,Mei Pan,Yuezhong Meng
A series of salicylaldiminato-zinc and -tri-zinc complexes containing various Schiff base ligands were prepared using quick methods and then well identified by full characterization. All zinc complexes were examined as catalysts for the copolymerization of CO2 and cyclohexene oxide. Many factors such as electron-donating or -withdrawing substituents on the benzene rings of the ligands, as well as chloride anions or acetate groups bound to the zinc centers, are found to greatly influence on the insertion of CO2 and ring-opening of epoxides. Tri-metallic complexes 2a and 2b exhibited excellent catalytic activities, and thus the copolymerization conditions such as temperature, pressure and reaction time were optimized. The molecular weights of the resulting copolymers determined by gel permeation chromatography display a bimodal distribution with relatively wide polydispersities. The results of the investigation indicate that the catalytic activities of zinc complexes are highly dependent on the electronic density and steric environment around the Zn metal centers.
研究领域:
化学
·
材料科学
·
催化反应
✓ 已验证
DOI
高影响因子
JOURNAL OF COORDINATION CHEMISTRY
·
2020
·
IF 1.41
Ting-Ting Zang,Jia-Peng Cao,Ze-Yu Du,Hua Mei,Yan Xu
Two new Schiff-base modified vanadium complexes, [VIVO(C7 H5O)2(N2C6H10)] (1) and [VVO2(C7H5O)(N2C6H12)] (2), were synthesized under hydrothermal conditions, in which salicylaldehyde and cyclohexanediamine were used directly to form Schiff-base ligands during the reactions. The structures of 1 and 2 were characterized by EA, FT-IR, UV-vis, SCXRD and PXRD, EPR spectroscopy and magnetic susceptibility measurement. Due to the good optical activity of Schiff-base ligands and the existence of conjugated benzene rings in 1 and 2, the delocalized electronic effects between Schiff-base ligands and vanadium can be improved. Therefore, the third-order non-linear optical (NLO) properties of these complexes were investigated. The results of the open aperture Z-scan tests show that the two-photon absorption (TPA) cross-sections (σ) of the complexes are 1033 and 1041GM, respectively, which indicated that they both have potential applications as NLO materials.
研究领域:
化学
·
材料科学
✓ 已验证
DOI
高影响因子
INORGANICA CHIMICA ACTA
·
2024
·
IF 2.7
Hou Cong Li,Ye Fan Zheng,Ming Zhu Wang,Chen Chen Geng,Min Hou,Chang Qing Liu,Wen Ge Li
Two new ligands, 2-(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)phenol (H 2 L1′) and 2-(5,6-dihydrobenzo[4,5]imidazo[1,2-c]quinazolin-6-yl)-4-fluorophenol (H 2 L2′) were synthesized by 2-(2-aminophenyl)benzimidazole with salicylaldehyde and 5-fluorosalicylaldehyde, respectively. While the two ligands (H 2 L1′ and H 2 L2′) were coordinated with nickel (II) and cobalt (II) ions and represented open-chain Schiff base structures (H 2 L1 and H 2 L2). Their metal complexes: [Ni 2 (HL1) 2 (C 2 H 5 OH) 2 Cl 2 ]‧2C 2 H 5 OH (complex 1), [Co (HL1) (L1)] (complex 2), [Ni 2 (HL2) 2 (C 2 H 5 OH) 2 Cl 2 ]‧2C 2 H 5 OH (complex 3) and [Co (HL2) (L2)] (complex 4) were obtained by solvothermal reaction. The four Schiff base complexes were characterized by infrared spectroscopy, elemental analysis, thermal stability analysis, X-ray powder diffraction, single-crystal X-ray diffraction, and lipophilicity assay. Single crystal X-ray analysis reveals that complexes 1 and 3 crystallize in a monoclinic system with space group P 21/n, while complexes 2 and 4 crystallize in a trigonal system with space group R -3. The lipophilicity assay (Log P) showed that the introduction of fluorine atoms enhanced the lipophilicity of ligands and complexes. The MTT method was used to determine the IC 50 values of complexes, ligands, and cisplatin against four different tumor cells (A-549, SMMC-7721, MDA-MB-231, and CNE-2Z) and one normal cell (IOSE 80). The results indicated that the four complexes exhibited stronger anticancer efficacy than ligands, among which the fluorine-substituted Co (III) complex (complex 4) displayed greater cytotoxicity compared with cisplatin in inhibiting SMMC-7721, MDA-MB-231 cells and A-549 cells, respectively. In addition, complex 4 can increase intracellular reactive oxygen species levels, arrest cells in the G0/G1 phase, upregulate Bax levels, and downregulate Bcl-2 levels, inducing MDA-MB-231 cell apoptosis in a dose-dependent manner.
研究领域:
化学
·
医学
·
肿瘤学
✓ 已验证
DOI
高影响因子
Polymer Chemistry
·
2017
·Vol. 8
·期 32
·4680-4687
·
IF 5.375
Liuyan Tang,Xiuli Chen,Lei Wang,Jinqing Qu
Metallo-supramolecular hydrogels (MSH) with hydrophobic ligands were fabricated by a simple but versatile strategy. This strategy is expected to extend the selection of ligands in hydrogel systems and enables the forming hydrogels to have more attractive properties and applications. An amphiphilic polymer with a hydrophobic Schiff base ligand, poly(N,N-dimethylacrylamide-co-2-(benzylidene-hydrazonomethyl)-phenol) (P(DMA-co-BHMP)), was synthesized and self-assembled to micelles in aqueous solution. The addition of selected divalent metal ions (Cu2+, Co2+, Ca2+, Mn2+, Pb2+ and Fe2+) connected each micelle with metal–ligand coordination and resulted in gelation. The designed ligand with a pH sensitive Schiff base structure (BHMP) contributed to the pH-responsive properties of the prepared hydrogels. Rheological studies displayed that hydrogels crosslinked by Cu2+ (Cu-gel) were injectable and rapidly self-healing. The addition of competing ligands (EDTA and EDA) caused the degradation of Cu-gel. We also illuminated the reversible redox gel–sol transition of the hydrogel crosslinked by the resulting polymer and Fe2+ (Fe-gel). These self-healable and multi-stimuli responsive hydrogels have potential for biomedical and encapsulation–controlled release applications.
研究领域:
材料科学
·
生物医学工程
✓ 已验证
DOI
高影响因子
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