Green and Red Photoluminescent Manganese Bromides with Aminomethylpyridine Isomers

Abstract

Two positional isomers, 4-amino-3-methylpyridine and 3-amino-5-methylpyridine, produce 4-amino-3-methylpyridinium and 5-methylpyridin-3-aminium, respectively, under acidic conditions. The two protonated isomers create different hydrogen bonding networks, resulting in different coordination environments of the [MnX4]2– unit embedded in molecular compounds such as 4-amino-3-methylpyridinium manganese bromide, [(C6H9N2)2MnBr4] and 5-methylpyridin-3-aminium manganese bromide, [(C6H9N2)4MnBr4(H2O)·(MnBr4)]. Both compounds can be prepared using the slow evaporation method or mechanochemical synthetic procedures. Single-crystal structure analysis of [(C6H9N2)2MnBr4] and [(C6H9N2)4MnBr4(H2O)·(MnBr4)] revealed different manganese halide units, including tetrahedral and tetrahedral with distorted trigonal bipyramidal structures, which emit photoluminescence in the green (527 nm) and red (607 nm) regions, respectively. Electronic structure calculations were conducted to support the validity and interpretation of the UV–vis and photoluminescence (PL) spectral data. Thin films deposited using the [(C6H9N2)2MnBr4] precursor also exhibit PL properties. The diverse pseudo-three-dimensional networks can be constructed by using positional isomers with different hydrogen bonding pathways and π–π stacking of organic units, in which the design strategy successfully enables the tuning of various optical properties.

Designing Optical Anisotropy: Silver-Aminoalkylpyridine Nitrate Complexes with Tunable Structures

“…Organic–inorganic hybrid materials (OIHMs) could effectively overcome these limitations and serve as an excellent choice for birefringent material strategies. OIHMs have garnered considerable interest due to their structural adaptability, which spans a broad spectrum of dimensional arrangements, ranging from zero to higher-dimensional framework structures, achieved by employing both metal nodes and organic linkers. − In particular, the interaction between the d-orbital electrons of a metal cation and the π-conjugated system can influence the shape and orientation of the electron orbitals, energy levels, electron distribution, and dipole moment of the metal complex. These factors can impact how the electric field of light interacts with the material, potentially altering the polarization and refraction of the light .…”