42 members new hydroquinone bridged supramolecular macrocycle and its tetra-nuclear mixed ligands Pt(II) complex: A synthetic, structural and spectroscopic investigation

Abstract

42 members supramolecular macrocycle (H4M) was synthesized in a simple one-step 2 + 2 condensation of 2,5‑diformyl hydroquinone with 4,7,10‑trioxa‑1,13‑tridecanediamine. The macrocycle was isolated in good yield by simple filtration and washing from the final reaction mixture. H4M has multiple salicylaldimine ON-donor sockets in the aromatic salicylaldimine part and six “O” atoms in ethylene glycol chains for transition or alkali metals or other cationic species binding. Preliminarily, this macrocycle was used in the synthesis of trans-tetra-platinum mono-chloride mixed ligand complex (M-4Pt(pyridine)Cl). The UV–vis analysis of this complex showed characteristic absorption around λmax = 593 nm visible region. Similarly a dimetallic quinone bridged control complex L-2Pt(pyridine)Cl bearing two Pt metals was prepared to better understand the structural orientation of the supramolecular macrocyclic complex (M-4Pt(pyridine)Cl). The structure of this control complex was determined by single crystal X-ray. Comparative UV analysis of M-4Pt(pyridine)Cl and L-2Pt(pyridine)Cl showed that the absorption of the same concentration of tetra-metallic macrocyclic complex was more than two times (ɛ = 7.0 × 10−3 mol−1 cm−1) to that observed for dimetallic control complex (ɛ = 3.1 × 10−3 mol−1 cm−1). The extremely simple productive synthetic and isolation procedure and the presence of multiple donor atoms promises to make this macrocycle an appealing platform in organometallic and supramolecular chemistry.