New europium coordination polymers with efficient energy transfer from conjugated tetracarboxylate ligands to Eu3+ ion: syntheses, structures, luminescence and magnetic properties was written by Wang, Li-Feng;Kang, Ling-Chen;Zhang, Wen-Wei;Wang, Fang-Ming;Ren, Xiao-Ming;Meng, Qing-Jin. And the article was included in Dalton Transactions in 2011.Formula: C12H10O4 This article mentions the following:
Two novel lanthanide coordination polymers, [Eu2(EBTC)(DMF)5(NO3)2]·DMF (1) and [Eu2(BBTC)1.5(CH3OH)2(H2O)2]·7DMF·HNO3 (2) (EBTC4- = 1,1′-ethynebenzene-3,3′,5,5′-tetracarboxylate; BBTC4- = 1,1′-butadiynebenzene-3,3′,5,5′-tetracarboxylate), were successfully synthesized from conjugated ligands of EBTC4- and BBTC4-. Although the two tetracarboxylate ligands have similar structures, their different rigidity/flexibility results in quite different networks upon complexation. Complex 1 has a two-dimensional (2-D) layered structure with two crystallog. independent Eu3+ ions, one in a distorted monocapped square-antiprism and the other in a distorted square-antiprism coordination geometry. Complex 2 exhibits a three-dimensional (3-D) porous framework, with one type of Eu3+ in a distorted square-antiprism and the other in a trigondodecahedron environment. Both 1 and 2 emit the intensely red characteristic luminescence of Eu3+ ion at room temperature, with a long lifetime of up to 1.3 and 0.7 ms, resp., during which the ligand emission of EBTC4-/BBTC4- was quenched by the Eu3+ ion, indicating the existence of efficient energy transfer between the conjugated ligand of EBTC4-/BBTC4- and the Eu3+ ion. Thus, both EBTC4- and BBTC4- are ideal ligands with an “antenna” effect for the Eu3+ ion. The two complexes show the single-ion magnetic behaviors of Eu3+ with strong spin-orbit coupling interactions even if there are shorter distances (5.714 Å for 1 vs. 4.275 and 5.360 Å for 2) between the neighboring Eu3+ ions connected by oxygen atoms of the tetracarboxylates. In the experiment, the researchers used many compounds, for example, Dimethyl 5-ethynylisophthalate (cas: 313648-56-5Formula: C12H10O4).
Dimethyl 5-ethynylisophthalate (cas: 313648-56-5) belongs to esters. Esters typically have a pleasant smell; those of low molecular weight are commonly used as fragrances and are found in essential oils and pheromones. Many esters have the potential for conformational isomerism, but they tend to adopt an s-cis (or Z) conformation rather than the s-trans (or E) alternative, due to a combination of hyperconjugation and dipole minimization effects. The preference for the Z conformation is influenced by the nature of the substituents and solvent, if present. Lactones with small rings are restricted to the s-trans (i.e. E) conformation due to their cyclic structure.Formula: C12H10O4
Referemce:
Ester – Wikipedia,
Ester – an overview | ScienceDirect Topics