Synthesis, structural characterization, and antimicrobial evaluation of new mononuclear mixed ligand complexes based on furfural-type imine ligand, and 2,2'-bipyridine

Manipulation of Bowl-Shaped Nanoparticles Self-Assembled from a Bipyridine Pendant Containing Homopolymer

The morphological control and transformation of soft nanomaterials are critical for their physical and chemical properties, which can be achieved by dynamically regulating the hydrophilicity of amphiphilic polymers during self-assembly. Herein, an amphiphilic homopolymer poly(N-(2,2'-bipyridine)-4-acrylamide) (PBPyAA) with bipyridine pendants is synthesized, and the effect of various parameters including initial concentration, temperature, pH, and metal ion coordination on the self-assembly behavior and morphology of the assemblies is investigated. Upon changing the initial concentration of PBPyAA, bowl-shaped nanoparticles (BNPs) with precisely controlled diameter, opening size, and thickness are obtained. With the decrease of pH of the solution, the negatively charged surface of BNPs transforms to a positively charged state. Furthermore, the addition of divalent metal ions (Co2+, Mn2+, and Zn2+) induces the transformation of BNPs to vesicles and giant vesicles. The effect of the above factors on the morphology of the assemblies is essential to change the hydrophilicity of PBPyAA dynamically, leading to variation of the local viscosity during self-assembly. Overall, manipulation of the structural parameters of BNPs and transformation of BNPs to vesicles are achieved, providing fresh insights for the precise control of the morphologies of soft nanomaterials.

Metal-ligand synergy driven functionalisation of alkylene linked bis(aldimine) on a diruthenium(II) platform. Cyclisation versus oxygenation

This article addresses the impact of metal-ligand redox cooperativity on the functionalisation of coordinated ligands. It demonstrates the structure-reactivity correlation of bis(aldimine) derived bis-bidentate L (Py-CHN-(CH2)n-NCH-Py, with n = 2 (L1), 3 (L2), 4 (L3)) as a function of the conformation (syn/anti) of its alkylene linker as well as the overall structural form (cis/trans) of (acac)2RuII(μ-L)RuII(acac)2 complex moieties (1-5) possessing an electron-rich acetylacetonate (acac) co-ligand. A systematic variation of the bridging alkylene unit of L in RuII/RuII-derived 1-5 led to the following reactivity/redox events, which were validated through structural, spectroscopic, electrochemical and theoretical evaluations: (i) Cyclisation of the ethylene linked (syn conformation) bis-aldimine unit of L1 via C-C coupling yielded pyrazine bridged (acac)2RuII(μ-L1')RuII(acac)2, 1a, while the corresponding anti-form (ethylene linker) of the metal-bound L1 in 2 ((acac)2RuII(μ-L1)RuII(acac)2) led to oxygenation at the ligand backbone (bis-aldimine (L) → bis(carboxamido) (L'')) via O2 activation to generate RuIIIRuIII-derived (acac)2RuIII(μ-L1''2-)RuIII(acac)2 (2a). (ii) Consequently, propylene and butylene linked L2 and L3 bridged between two {Ru(acac)2} units in 3 and 4/5 underwent oxygenation of L to L'' to yield diruthenium(III) complexes 3a and 4a/5a, respectively. (iii) In contrast, analogous L bridged oxidised [(acac)2RuIII(μ-L)RuIII(acac)2](ClO4)2 ([2](ClO4)2-[5](ClO4)2) and [{(PPh3)2(CO)(H)RuII}2(μ-L)](ClO4)2 ([6](ClO4)2-[8](ClO4)2) involving electron poor co-ligands failed to undergo the oxygenation of L irrespective of its n value, reemphasising the effective role of redox interplay between RuII and L particularly in the presence of an electron-rich acac co-ligand in the functionalisation of the latter in 1a-5a.