LAUSR

Abstract Under hydrothermal conditions, a novel bimetallic thulium–mercury compound {[Tm(H 2 O) 2 (IA) 3 ] 2 n [(Hg 6 Br 13 ) n ]}( n HgBr 2 )·4 n H 2 O· n H 3 O ( 1 ) (IA = isonicotinato anion) was prepared and the crystal structure was characterized by single-crystal and powder X-ray diffraction. It is characterized by a three-dimensional (3D) framework with a novel two-dimensional (2D) inorganic [(Hg 6 Br 13 ) n ] layer. Solid-state photoluminescence measurements revealed that compound 1 emits upconversion mazarine emission bands, which are originated from the 1 G 4  →  3 H 6 and 1 D 2  →  3 H 4 characteristic emissions of the 4 f electron intrashell transitions of Tm(III) ions. An energy transfer mechanism is reported. Compound 1 displays CIE chromaticity coordinates of 0.1288 and 0.0635 in the mazarine region. A solid-state UV–Vis–NIR diffuse reflectance spectrum unveiled that compound 1 has a wide optical band gap of 2.69 eV. A thermogravimetry analysis measurement is also reported. Graphic abstract A novel bimetallic thulium–mercury compound was prepared and characterized. It features a 3D framework with a novel 2D inorganic [(Hg 6 Br 13 ) n ] layer. It contains many mercury(II) ions with four different coordination environments. It emits upconversion mazarine photoluminescence emission peaks, which could be attributed to the 1 G 4  →  3 H 6 and 1 D 2  →  3 H 4 characteristic emissions of the 4 f electron intrashell transitions of the Tm(III) ions. An energy level diagram was used to explain the energy transfer mechanism. It has CIE chromaticity coordinates of 0.1288 and 0.0635 in the mazarine region, and it possesses a wide optical band gap of 2.69 eV.