Two temperature-dependent Cd(II)-based coordination polymers with mixed adenine nucleobase and benzene-1,4-dicarboxylic acid: synthesis, structures and fluorescence properties

Abstract

Two Hade-based Cd(II) polymers, [Cd(Hade)(tp)] _n (1) and {[Cd₆(Hade)₆(tp)₆]·9H₂O} _n (2) (Hade = adenine, H₂tp = benzene-1,4-dicarboxylic acid), were obtained from the same reaction system at different temperatures which have been characterized by single-crystal X-ray diffraction, elemental analysis, FT-IR spectroscopy, thermogravimetric analysis, and luminescence spectroscopy. Significantly resulting from the synergistic coordination of nucleobase and bicarboxylate groups, they are a 3-D pillared-layer structure for 1 and a 2-D grid structure where the dicadmium paddle-wheel motifs are double bridged by benzene-1,4-dicarboxylate anions for 2. The supramolecular architecture of 2 is essentially knitted by hydrogen bonding interactions produced by the exocyclic amino/endocyclic imino groups of the nucleobase and the carboxylate groups of the co-ligand to favorably stabilize the high-dimensional supramolecular architectures. At room temperature, 1 and 2 exhibit intense luminescent emissions originating from a Hade-based intraligand and/or photoinduced charge transfer upon adenine binding mode.

Graphical Abstract

Keywords:

• Adenine
• benzene-1,4-dicarboxylic acid
• Cd(II) polymer
• crystal structure
• Fluorescence property

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the National Natural Science Foundation of China (grants 21671149, 21571140 and 21531005), which are gratefully acknowledged.