Synergetic Spin-Crossover and Luminescent Properties in a Multifunctional 2D Iron(II) Coordination Polymer.

We designed and synthesized a strong fluorescent tetradentate pyridine ligand, 3,6,11,12-tetra(pyridin-4-yl)dibenzo[ a , c ]phenazine (TPDP), by covalently grafting pyridyl to fluorescent dye dbpz, which can react with the Fe(NCX) 2 (X = S and Se) unit, obtaining two new 2D [4 × 4] square-grid compounds, namely, {Fe II (TPDP) 2 (SCN) 2 ·CHCl 3 ·4CH 3 OH} n ( 1 ) and {[Fe II (TPDP) 2 (SeCN) 2 ]·CH 2 Cl 2 ·4CH 3 OH} n ( 2 ). Both of them show expected one-step spin-crossover (SCO) properties, and complex 2 vacuum exhibits a combination of the SCO phenomenon and fluorescence in a synergetic way. The energy transfer mechanism of 2 vacuum is verified by the theoretical calculations and experimental results. This study provides an effective strategy to synthesize large conjugated fluorescent ligands using dyes to further form SCO-luminescent bifunctional materials.