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Abstract Reactions of 3-fluoro-N-methylbenzylamine (FBMA) with PbBr 2 in concentrated HBr aqueous solution afforded a two-dimensional (2D) single layered organic-inorganic hybrid material [(FBMA) 2 PbBr 4 ], which was confirmed by X-ray single crystal diffraction, infrared (IR) spectroscopy and powder X-ray diffraction (PXRD). The thermodynamic DSC analysis revealed it has a pair of reversible phase transition peaks with large thermal hysteresis exhibiting a first-order type phase transition. The variable-temperature single crystal diffraction proved the phase transition is originated from the order and disorder of organic-inorganic hybrid structures at room and high temperatures. Simultaneously compound [(FBMA) 2 PbBr 4 ] exhibited a strong emission peak at 443 nm when under an excitation wavelength of 380 nm. Graphic abstract A new two-dimensional (2D) single layered organic-inorganic hybrid material (FC 6 H 4 CH 2 NH 2 CH 3) 2 [PbBr 4 ] showed a first-order type phase transition, which was originated from the order-disorder transition of organic-inorganic hybrid structures at room and high temperatures. fx1 Highlights • A new layered organic-inorganic-hybrid perovskite is designed, synthesized, and characterized. • The relationship between phase transitions and structural changes is addressed. • The optical property of (FC 6 H 4 CH 2 NH 2 CH 3) 2 [PbBr 4 ] is studied. [ABSTRACT FROM AUTHOR]

Two inorganic–organic hybrid compounds [(C 7 H 18 N 2 ) 6 Pb 7 I 26 ] ( 1 ) and [(C 7 H 18 N 2 )Pb 2 I 6 ] ( 2 ) have been synthesized by reactions of 2-(2-aminoethyl)-1-methylpyrrolidine and lead iodide with 1: 1 and 1: 2 M ratios in concentrated HI aqueous. The single-crystal X-ray diffraction revealed that the inorganic component in compound 1 can be viewed as a wave-like 2D sheet built up from alternatively perovskite and non-perovskite structure types connected with corner-, edge- sharing octahedral [PbI 6 ]; and that in complex 2 is a zigzag chain constructed with edge- sharing octahedral [PbI 6 ]. In addition, both complexes showed fluorescent properties with complex 1 emitted green light at 545 nm and complex 2 emitted blue light at 467 nm. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) organic-inorganic hybrid perovskite (OIHP) has the advantages of excellent material stability, structural diversity and ease of manufacturability. It is worth noting that the fluorination strategy has been recognized as a convenient molecular design method that can effectively customize and optimize physical and chemical properties in 2D OIHP materials. However, selection the fluorine-chlorine double substituted organic amine to construct lead halide OIHP molecules was not reported. Here, for the first time, we successfully obtained a 2D metal halide perovskite compound [4-Cl-2-FBA] 2 PbBr 4 (1) by reactions of lead bromide with two equivalents of 4-chloro-2-fluorobenzylamine [4-Cl-2-FBA] in concentrated HBr aqueous solution. Its crystal structure and purity were confirmed by X-ray single crystal diffraction and powder X-ray diffraction (PXRD). Differential scanning calorimetry (DSC) and dielectric measurement analyses showed the phase transition (PT) temperature of 1 is 380.1 ​K which is higher than that of [2-FBA] 2 PbBr 4 , (2-FBA ​= ​2-fluorobenzylammonium, 364 ​K), but lower than those of (benzylammonium) 2 PbBr 4 (405 ​K) and [PFBA] 2 PbBr 4 (PFBA ​= ​perfluorobenzylammonium, 440 ​K). A two-dimensional (2D) organic-inorganic hybrid perovskite material [4-Cl-2-FBA] 2 PbBr 4 (1) with high phase transition temperature and semiconductive property was isolated by reactions of lead bromide with two equivalents of 4-chloro-2-fluorobenzylamine [4-Cl-2-FBA] in concentrated HBr aqueous solution. [Display omitted] • A fluorine and chlorine substituted 2D metal halide perovskite was firstly prepared by reactions of PbBr 2 ​with 4-chloro-2-fluorobenzylamine. • DSC analysis showed the phase transition temperature of ​ 1 ​is 380.1 K which is higher than that of [2-FBA] 2 PbBr 4 ​at 364 K. • The 2D metal halide perovskite was characterized by the variable temperature X-ray single crystal diffraction. [ABSTRACT FROM AUTHOR]