Photoluminescent cuprous iodide polymorphs generated via in situ organic reactions

•Two cuprous iodide polymorphs were synthesized via in situ templation.•X-ray crystallography reveals that two polymorphs have different conformations.•The UV–vis spectra exhibit that polymorphs belong to optional semiconductors.•Two polymorphs show different photoluminescent emission and excitation.

Two cuprous iodide polymorphs formulated as [N(CH3)4][Cu2I3] α and β were synthesized, in which N(CH3)4+ template that never existed in the reaction materials are in situ generated via cleavage of CN bonds and N-alkylation reactions. Solvothermal reaction of copper source, hexamethylenetetramine and HI in methanol solution at 150 °C led to α and β polymorphs. Two polymorphs have been synthesized via subtle modification of the experimental condition, which indicates that the small force is also sufficient for energy difference for polymorphs. α polymorph contains one-dimensional Cu2I3− chain in which the copper atoms are arranged into a zigzag lattice; β polymorph is composed of novel ladder-like chains which can be considered as being built up by Cu12I18 and Cu2I3 two types of secondary building units. The UV–vis absorption spectra for α and β polymorphs were investigated in reflectance mode in the solid state at room temperature, exhibiting that they belong to potential semiconductors. The excitation and emission in α and β are very distinct, which highlight that the molecular packing in polymorphs is critical to photophysical properties.

Graphical abstractTwo cuprous iodide polymorphs formulated as [N(CH3)4][Cu2I3] α and β were synthesized, in which N(CH3)4+ template that never existed in the reaction materials are in situ generated via cleavage of CN bonds and N-alkylation reactions. α contains one-dimensional Cu2I3− chain in which the copper atoms are arranged into a zigzag lattice; β is composed of novel ladder-like chains which can be considered as being built up by Cu12I18 and Cu2I3 two types of units. Two polymorphs have been synthesized via subtle modification of the experimental condition, which indicates that the small force is also sufficient for energy difference for polymorphs.Figure optionsDownload full-size imageDownload as PowerPoint slide