Zinc/itaconate coordination polymers as first examples with long-lasting phosphorescence based on acyclic ligands

• Published in: Journal of materials chemistry. C, Materials for optical and electronic devices Vol. 6; no. 40; pp. 10870 - 10880
• Main Authors: Wibowo, Atmanto Heru, Suryandari, Yetti, Masykur, Abu, Pérez-Yáñez, Sonia, Rodríguez-Diéguez, Antonio, Cepeda, Javier
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 2018
• Subjects: Chemical compounds; Coordination polymers; Crystallography; Density functional theory; Fluorescence; Fourier transforms; Ligands; Mathematical analysis; Organic chemistry; Phosphorescence; Photoluminescence; Polymers; Single crystals; Spectrum analysis; Time dependence; Zinc coordination
• ISSN: 2050-7526; 2050-7534
• DOI: 10.1039/C8TC03598A

Two novel coordination polymers (CPs) based on zinc( ii ) and acyclic dicarboxylate linkers, i.e. [Zn 2 (μ 3 -IA) 2 (H 2 O) 4 ] n ( 1-W ) and {[Zn 2 (μ-IA) 2 (DMF)]·H 2 O} n ( 2-DMF ) (where IA 2− = itaconate) have been obtained as a result of a systematic study of some synthetic factors such as pH and solvents, which has allowed optimizing the conditions that render the best yields. 1-W is obtained as X-ray quality single crystals upon which diffraction analysis has been conducted, showing that it consists of a neutral 2D layered structure. Some structural details have been elucidated for 2-DMF based on a comparison of PXRD data with 1-W and in view of the similar composition of both crystalline phases. Photoluminescence (PL) measurements confirm that 2-DMF presents slightly different spectra from those of 1-W . Time-dependent density functional theory (TD-DFT) calculations of 1-W reveal that electronic transitions arise from both first excited singlet and triplet states involving ligand-centred emissions. Moreover, both compounds exhibit blue fluorescence and green phosphorescence that involves less frequent long-lasting phosphorescence (LLP) at 10 K. Exhaustive characterization of long-lasting phosphorescence by means of time-resolved spectroscopy reveals remarkably long lifetimes ( τ ) of ca. 352 ms ( λ em ≈ 550 nm) for 1-W and 547 ms ( λ em ≈ 500 nm) for 2-DMF .