New thiocyanatocadmates templated by multi-dentate N-heterocyclic/diamine molecules

Abstract

With diverse multi-dentate N-heterocyclic/diamine molecules as the cations, the reactions between Cd²⁺ and SCN⁻ in C₂H₅OH/H₂O solution acidified by H₂SO₄ created five new thiocyanatocadmates [H₂(bim)][Cd(SCN)₂(H₂O)₂]SO₄ (bim = 2,2′-biimidazole) 1, [H₂(pympip)]₂[Cd₂(SCN)₄(SO₄)₂(H₂O)₄]·2H₂O (pympip = 1-(2-pyrimidyl)piperazine) 2, [H₂(tdpy)]₂[Cd₃(SCN)₁₀] (tdpy = 4,4′-thiodipyridine) 3, [H₂(badpm)][Cd(SCN)₄] (badpm = 4,4′-biaminodiphenylmethane) 4 and [H₂(pdma)][Cd₂(SCN)₄(SO₄)] (pdma = 1,4-phenylenedimethanamine) 5. It is noteworthy that (i) in compounds 1, 2 and 5, SO₄²⁻ was incorporated into the organically templated thiocyanatocadmate frameworks; (ii) compound 3 is a rare example, in which two types of chained thiocyanatocadmates are found, and (iii) compound 5 shows an interesting layer structure, constructed up from the ribboned thiocyanatocadmates by μ₂-mode SO₄²⁻. Photoluminescence analysis revealed that compounds 1, 2 and 5 in solid state emit blue light with the maximum at 425 nm for 1, 405 nm for 2 and 445 nm for 5, respectively.