Central-metal exchange, improved catalytic activity, photoluminescence properties of a new family of d10 coordination polymers based on the 5,5′-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid ligand?

Dalton Transactions Pub Date: 2016-03-29 DOI: 10.1039/C6DT00726K

Abstract

The rigid and planar tetracarboxylic acid 5,5′-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid (H4L), incorporating a triazole group, has been used with no or different pyridine-based linkers to construct a family of d10 coordination polymers, namely, {[H2N(CH3)2]3[Cd3(L)2(HCOO)]}n (1), {[Cd2(L)(py)6]·H2O}n (2), {[H2N(CH3)2] [Cd2(L)(HCOO)(H2O)4]}n (3), {[Zn(H2L)]·H2O}n (4), and {[Zn(H2L)(4,4′-bipy)0.5]·C2H5OH·H2O}n (5) (py = pyridine, 4,4′-bipy = 4,4′-bipyridine). 1 constructs a 3D porous network containing two kinds of channels: one is filled with coordinated HCOO? anions, and the other with [H2N(CH3)2]+ cations. The framework of 1 can be described as a rare (5,6,7)-connected net with the Schl?fli symbol of (412·5·62)(45·53·62)2(48·53·68·82)2. The Cd(II) ions in 2 are connected through the carboxylate ligands to form a 2D layer, with aperture dimensions of ～15.1 ? × 16.2 ?. The network of 3 features a 3D (3,4)-connected (6·8·10)2(6·83·102) topology. A 3D network with the (42·6·83) topology of 4 possesses an open 1D channel with the free volume of 29.2%. 5 is a 2D layer structure with the (42·63·8)(42·6) topology. The fluorescence lifetime τ values of 1–5 are on the nanosecond timescale at room temperature. In particular, central-metal exchange in 2 leads to a series of isostructural M(II)–Cd frameworks [M = Cu (2a), Co (2b), Ni (2c)] showing improved catalytic activity for the synthesis of 1,4,5,6-tetrahydropyrimidine derivatives. Based on this, a plausible mechanism for the catalytic reaction has been proposed and the reactivity–structure relationship has been further clarified.

Graphical abstract: Central-metal exchange, improved catalytic activity, photoluminescence properties of a new family of d10 coordination polymers based on the 5,5′-(1H-2,3,5-triazole-1,4-diyl)diisophthalic acid ligand
Recommended Literature