A highly connected (5,5,18)-c trinodal MOF with a 3D diamondoid inorganic connectivity: Tunable luminescence and white-light emission

A new heterometallic MOF, namely [Cd₂K₄(2,3-PDC)₄] (1) (2,3-H₂PDC = 2,3-pyridine dicarboxylic acid), has been successfully synthesized from Cd²⁺ and K⁺ salts with 2,3-H₂PDC under the solvothermal conditions. Single crystal X-ray diffraction studies reveal that 1 is a three-dimensional, highly connected trinodal (5,5,18)-c net. Compound 1 features a rare 3D diamondoid Cd(ii)-K(i) inorganic connectivity constructed by a {Cd₂K₄} cluster. The K⁺ ion in the structure functions not only as a charge balancer but also as a connector in the construction of MOF. Tunable blue-green to white luminescence of 1 was achieved by variation of the excitation wavelength and the inclusion amount of Eu³⁺ ions in the host framework of 1.