Photoluminescence and Nonlinear Optical Properties of Two Terpyridine-Based Hybrid Zn/Cd Halides.

Hybrid metal halides (HMHs) with low-dimensional structures have attracted increasing attention due to their striking optical properties. Herein, two new zero-dimensional HMHs have been fabricated by CdCl2/ZnCl2 and 4'-(4-pyridyl-phenyl)-2,2':6',2″-terpyridine (Tpy), including (TpyH3)[CdCl4][Cl] (Tpy-Cd) and (TpyH3)[ZnCl4][Cl] (Tpy-Zn). Their structures are consisted of a [TpyH3]3+ organic cation, an inorganic [ZnCl4] or [CdCl4] tetrahedron, and one isolated Cl- anion. Tpy-Cd crystallizes to a noncentrosymmetric structure and possesses a moderate second harmonic response of 0.72 × KH2PO4, while Tpy-Zn features a centrosymmetric space group. Though Tpy-Cd and Tpy-Zn crystallize into space groups of completely different symmetry due to distinct connection mode and molecular distortion, they display quite similar photoluminescence of bright green light emission under ultraviolet excitation, nearly identical in Stokes shift, photoluminescence quantum yield, decay lifetime, and energy. The photoluminescence quantum yields of green light emission were measured to be nearly 25%, outperforming most of the Cd/Zn low-dimensional HMHs.

Fe(II) complexes of 2,2':6',2''-terpyridine ligands functionalized with substituted-phenyl groups: synthesis, crystal structures and anticancer potential.

With the aim of developing potential anticancer drug candidates, a series of Fe(II) complexes were synthesized using nine 2,2':6',2''-terpyridine ligands functionalized with substituted-phenyl groups, and their biological activities were systematically investigated. Their bis-terpyridine sandwich-like structures were determined by single crystal X-ray crystallography. In vitro antiproliferative experiments based on three human cancer cell lines, including human hepatoma cancer cell line (Bel-7402), human esophageal cancer cell line (Eca-109), and human cervical squamous cancer cell line (SiHa), indicate the high antiproliferation activities of these complexes compared with commercial cisplatin. And their toxicity to normal cells was estimated based on human normal hepatocyte (HL-7702) cell line. In particular, when the phenyl in terpyridine ligand was modified by a carboxyl group, the corresponding complex 3 exhibited much higher antiproliferation to cancer Bel-7402 cells (IC50 = 3.653 µmol L-1) than cisplatin and low toxicity to normal HL-7702 cells (IC50 = 99.92 µmol L-1), implying a significant selectivity for 3 in killing hepatoma cancer cells. Combined with the fact that iron element is more accessible than platin, this series of Fe(II) complexes comprises potential candidates for anticancer drugs with specific inhibition of hepatoma cancer. UV titration experiments and circular dichroism (CD) showed a strong binding affinity between these nine complexes and CT-DNA. However, molecular docking simulation revealed the competitive binding of DNA and protein to these complexes. Further, the interactions between these complexes and bovine serum albumin (BSA) have been studied by fluorescence titration and CD spectroscopy.