Synthesis, X-ray crystal structure, optical properties and DFT studies of a new 2D layered iodide bridged Pb(II) coordination polymer with 2,3-bis(2-pyridyl)pyrazine

•Two dimensional [Pb2(µ-I)2(µ-dpp-N,N,N,N)(µ-dpp-N,N)I2]n has been prepared.•The structure of the compound is determined by XRD of a twinned crystal.•DFT calculations indicate that the compound is an indirect band gap semiconductor.•As shown by DFT calculations, the emission band of the compound is LLCT.•Solution phase structure of compound is explored by 1H NMR and emission spectra.

The synthesis of two dimensional (2D) coordination polymer [Pb2(µ-I)2(µ-dpp-N,N,N,N)(µ-dpp-N,N)I2]n (dpp=2,3-bis(2-pyridyl)pyrazine) is reported. As determined by X-ray diffraction of a twinned crystal, the dpp ligand simultaneously adopts a bis–bidentate and bis–monodentate coordination mode in the crystal structure of compound. The electronic band structure along with density of states (DOS) calculated by the DFT method indicates that the compound is an indirect band gap semiconductor. According to the DFT calculations, the observed emission of the compound at 600 nm in solid phase could be attributed to arise from an excited LLCT state (dpp-π⁎ [C-2p and N-2p states, CBs] to I-6p state [VBs]). The linear optical properties of the compound are also calculated by DFT method. The structure of the compound in solution phase is discussed based on the measured 1H NMR and fluorescence spectra in DMSO. TGA studies indicate that the compound is thermally stable up to 210 °C.

Graphical abstractThe synthesis, crystal structure and emission spectra of [Pb2(µ-I)2(µ-dpp-N,N,N,N)(µ-dpp-N,N)I2]n is presented. The electronic band structure and linear optical properties of the compound are calculated by the DFT method.Figure optionsDownload full-size imageDownload as PowerPoint slide