Green and Red Photoluminescent Manganese Bromides with Aminomethylpyridine Isomers

초록

Green and red photoluminescenceof two manganese bromidecomplexes derived from different secondary interactions of aminomethylpyridineisomers is reported. Two positional isomers, 4-amino-3-methylpyridine and3-amino-5-methylpyridine,produce 4-amino-3-methylpyridinium and 5-methylpyridin-3-aminium,respectively, under acidic conditions. The two protonated isomerscreate different hydrogen bonding networks, resulting in differentcoordination environments of the [MnX4](2-) unit embedded in molecular compounds such as 4-amino-3-methylpyridiniummanganese bromide, [(C6H9N2)(2)MnBr4] and 5-methylpyridin-3-aminium manganesebromide, [(C6H9N2)(4)MnBr4(H2O)& BULL;(MnBr4)]. Both compoundscan be prepared using the slow evaporation method or mechanochemicalsynthetic procedures. Single-crystal structure analysis of [(C6H9N2)(2)MnBr4] and[(C6H9N2)(4)MnBr4(H2O)& BULL;(MnBr4)] revealed different manganesehalide units, including tetrahedral and tetrahedral with distortedtrigonal bipyramidal structures, which emit photoluminescence in thegreen (527 nm) and red (607 nm) regions, respectively. Electronicstructure calculations were conducted to support the validity andinterpretation of the UV-vis and photoluminescence (PL) spectraldata. Thin films deposited using the [(C6H9N2)(2)MnBr4] precursor also exhibit PL properties.The diverse pseudo-three-dimensional networks can be constructed byusing positional isomers with different hydrogen bonding pathwaysand & pi;-& pi; stacking of organic units, in which thedesign strategy successfully enables the tuning of various opticalproperties.

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