Three d10 based metal-organic frameworks constructed from 2-(3’,4’-dicarboxylphenoxy) isophthalic acid: Dual-functional luminescent sensors for Cu2+, Fe3+ cations and Aspartic acid

Abstract

A series of d10 based metal-organic frameworks (MOFs), namely, [Cd2(dpc)(bipy)(H2O)3]n (Ⅰ), {[Cd2(dpc)(bib)(H2O)]·H2O}n (Ⅱ), {[Cd2(dpc)(bitb)1.5(H2O)2]·H2O}n (Ⅲ) (H4dpc = 2-(3′,4′-dicarboxylphenoxy)isophthalic acid, bipy = 4,4′-dipyridyl, bib = 1,4-bis (1-imidazolyl)benzene, bitb = 1,4-bis (imidazol-1-ylmethyl)benzene) have been designed and successfully synthesized using a flexible tetrabasic carboxylic acid along with three ancillary ligands under hydrothermal conditions, which exhibit structural diversities of targeted Cd-MOFs. Single-crystal X-ray diffraction analysis reveals that they contain building units of {CdN1O6} and {CdN1O5} (for I), {CdN1O5} (for II), as well as {CdN2O4} and {CdN5O1} (for Ⅲ), based on which to assemble microporous three-dimensional (3D) frameworks via covalent bonds and/or hydrogen bonds using multiple coordination modes of H4dpc ligand and auxiliary linkers. The solid-state luminescence performances of these Cd-MOFs were investigated at ambient temperature. Furthermore, luminescent sensing responses of Ⅰ-Ⅲ to amino acids and metal cations were systematically explored. Notably, Ⅰ and II may act as potential dual-functional luminescent sensors for Aspartic acid and Cu2+ cations as well as Aspartic acid and Fe3+ cations with high selectivity and sensitivity in aqueous solutions, respectively. The mechanisms of the quenching effect and sensing properties of the as-synthesized Cd-MOFs have also been discussed in this report.