Two organic-inorganic manganese(II) halide hybrids containing protonated N,N’-dialkylthioureas with efficient green-emission

Golovnev, N.N., Gerasimova, M.A., Ostapenko, I.A., Zolotov, A.O., Molokeev, M.S.// Journal of Molecular Structure//

Luminescent (C5H13N2S)2[MnBr4] (1) and (C7H17N2S)2[MnBr4] (2) (C5H12N2S = N,N′-diethylthiourea, C7H16N2S = N,N′-diisopropylthiourea) were prepared via solvothermal method, and the structures of these compounds have been resolved using X-ray single crystal diffraction. The structures consist of electrostatically bound MnBr42− anions and organic C5H13N2S+ and C7H17N2S+ cations. The intermolecular N−H···Br and N−H···S hydrogen bonds additionally stabilize crystal structures of 1-2. Upon excitation over broadband covering the range 265 to 515 nm, these compounds show green emission peaking at 526 nm for 1 and 522 nm for 2, which is assigned to the 4T1 6A1 electronic transition of Mn2+ from isolated within the crystal structures MnBr42− tetrahedra. The photoluminescence quantum yield (PLQY) of powder 1 is 97 ± 7% for excitation at 440 nm and that of powder 2 is 83 ± 7% for excitation at 365 nm. The high PLQY indicates the absence of noticeable concentration quenching at shortest Mn···Mn distance of 8.11 and 8.73 Å between Mn2+ ions within the structures of 1 and 2. The high-performance photoluminescence of 0D (C5H13N2S)2[MnBr4] and (C7H17N2S)2[MnBr4] compounds demonstrated promising applications in photonics.