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A mixed amines thiogermanate (NH 4) 2 [NH 2 (CH 3) 2 2 Ge 2 S 6 was reported. Its structure features isolated [Ge 2 S 6 4− anions which are separated by NH 4 + and [NH 2 (CH 3) 2 +. UV–Vis diffuse reflectance spectroscopy coupled with Tauc's analysis indicates an indirect optical transition semiconductor with an energy gap value of 3.50 eV. Furthermore the energy transition type was supported by first-principles electronic structure calculation. A mixed amines thiogermanate, namely (NH 4) 2 [NH 2 (CH 3) 2 2 Ge 2 S 6 has been successfully synthesized by solvothermal reaction. Single crystal X-ray diffraction indicates the compound crystallizes in monoclinic space group P 2 1 / c with the lattice parameters: a = 6.9647(14) Å, b = 15.719(3) Å, c = 7.2042(14) Å, β = 92.76(3)°. The structure features a zero-dimensional [Ge 2 S 6 4− anions which are separated by NH 4 + and [NH 2 (CH 3) 2 +. Hydrogen bond interactions play a crucial role in its structure formation. X-ray powder diffraction and TG-DSC measurements were performed to study its phase purity and thermal stability. UV–Vis diffuse reflectance spectroscopy coupled with Urbach fitting indicates an indirect optical transition semiconductor with a bandgap value of 3.50 eV. The result of first-principles electronic structure calculation supported the experimental indirect optical transition but the value was under estimated as 3.061 eV. Density of states and population analysis were also calculated to reveal the origin of the bandgap and bond interaction for its structure formation. [ABSTRACT FROM AUTHOR]

Through the incorporation of Cu(II) ions as additional connecting nodes to form heterometallic uranyl-organic frameworks with rigid ligands, we have successfully synthesized three extended complexes with varying dimensions. Notably, complex 1 features a robust 3D cds net structure and demonstrates exceptional thermal stability above 250 °C. [Display omitted] By introducing Cu(II) ions as additional connecting nodes to construct stable heterometallic uranyl-organic frameworks (UOFs) with thiophene-2,5-dicarboxylic acid (H 2 TDC) and N -donor auxiliary ligands, three new uranyl complexes, namely, [Cu(phen)(UO 2)(TDC) 2 ] (1), [Cu(phen-NO 2) 2 (UO 2)(TDC) 2 ]·3H 2 O (2), and [Cu(phen-NH 2)(H 2 O) 2 (UO 2)(TDC) 2 ]·4H 2 O (3) (phen = 1,10-phenanthroline) have been successfully synthesized by hydrothermal reaction. Complex 1 exhibits a rare three-dimensional (3D) network structure of cds topology connected by UO 2 , Cu(phen), and TDC units. Both complexes 2 and 3 feature similar one-dimensional chain structures based on UO 2 , TDC, Cu(Phen-NO 2) 2 and UO 2 , TDC, Cu(phen-NH 2)(H 2 O) 2 respectively. The N -donor auxiliary ligands play a key role in determining their structural dimensionalities and bandgaps formation. Among the three uranyl complexes, phen with a smaller size than its derivatives, phen-NO 2 and phen-NH 2 , was found to be favorable for constructing 3D UOFs. Moreover, complexes with both phen-NO 2 and phen-NH 2 showed varying degrees of redshift on optical spectra. The UV–Visible diffuse-reflectance spectra, analyzed with Tauc's fitting in considering Urbach tailing, revealed an indirect bandgap of 2.94 eV, an indirect bandgap of 2.67 eV, and a direct bandgap of 2.45 eV for 1 , 2 and 3 , respectively. Moreover, thermogravimetric analyses indicate that 3D anhydrous uranyl complex 1 possessed a robust structure and excellent thermal stability above 250 ℃. [ABSTRACT FROM AUTHOR]