Zinc Coordination Polymers Containing Isomeric Forms of p-(Thiazolyl)benzoic Acid: Blue-Emitting Materials with a Solvatochromic Response to Water

Staderini S, Tuci G, Luconi L, Mueller P, Kaskel S, Eychmueller A, Eichler F, Giambastiani G, Rossin A (2017)

Publication Type: Journal article

Publication year: 2017

Journal

European Journal of Inorganic Chemistry Wiley-VCH Verlag

Book Volume: 2017

Pages Range: 4909-4918

Journal Issue: 42

DOI: 10.1002/ejic.201700830

Abstract

Two coordination polymers of assorted dimensionality (1D, 2D) have been prepared, namely [Zn3(L^2Th)4(OH)2·2(HL^2Th)]∞ (1) and [Zn(L^5Th)(OAc)]∞ (2), starting from Zn^II salts and the isomeric forms of the organic linker p-(thiazolyl)benzoic acid: p-(2-thiazolyl)benzoic acid (HL^2Th) and p-(5-thiazolyl)benzoic acid (HL^5Th). The isomers have been prepared ad hoc, following straightforward Pd-catalyzed C–C coupling reaction protocols. In 1, the deprotonated ligand is coordinated through its carboxylate group only, with dangling thiazole groups. The –COO^– units are bridging adjacent metal centers, thus creating a 1D chain. The Zn3 cluster is made of one six-coordinate (Oh) and two four-coordinate (Td) Zn^II ions; triple-bridging µ3-OH groups are balancing the overall positive charge. The structure of 2 is instead made of Zn2(carboxylate)4 “paddle-wheel” dimers as the constituting inorganic node. The octahedral metal coordination sphere includes two µ-(κ-COO) benzoate spacers, two µ-(κ-COO) acetate ions, the thiazole N atoms coming from adjacent building blocks, and a weak Zn···Zn axial interaction. The resulting final assembly is two-dimensional (2D), where p-(5-thiazolyl)benzoate adopts a genuine µ-[κ(COO):κ(N)] bridging coordination mode. The luminescent properties of both polymers have been analyzed in the solid state; they feature ligand-centered emissions at λ = 434 nm (1) and λ = 427 nm (2). These electronic transitions fall in the visible region, giving the samples a characteristic blue color under an ordinary UV lamp (excitation at λ = 254 nm). The theoretical analysis of the electronic features of the ligands and related molecular orbitals reveals that the observed transitions are mainly of π→π* nature, involving π orbitals delocalized on both aromatic cycles. A significant (reversible) blueshift of the emission maximum of ca. 60 nm, from the visible to the UV region, has been observed for 1 when suspended in water.

Involved external institutions

Consiglio Nazionale delle Ricerche (CNR) / National Research Council of Italy

Italy (IT) Technische Universität Dresden

Germany (DE)

How to cite

APA:

Staderini, S., Tuci, G., Luconi, L., Mueller, P., Kaskel, S., Eychmueller, A.,... Rossin, A. (2017). Zinc Coordination Polymers Containing Isomeric Forms of p-(Thiazolyl)benzoic Acid: Blue-Emitting Materials with a Solvatochromic Response to Water. European Journal of Inorganic Chemistry, 2017(42), 4909-4918. https://doi.org/10.1002/ejic.201700830

MLA:

Staderini, Samuele, et al. "Zinc Coordination Polymers Containing Isomeric Forms of p-(Thiazolyl)benzoic Acid: Blue-Emitting Materials with a Solvatochromic Response to Water." European Journal of Inorganic Chemistry 2017.42 (2017): 4909-4918.

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