Abstract
Solvothermal synthesis with manganese nitrate, p‐biphenyldicarboxylic acid, and three different solvents resulted in three new metal–organic framework materials: Mn(C~14~H~8~O~4~)(C~3~H~7~NO)~2/3~ (1), Mn~2~(C~14~H~8~O~4~)~3/2~(CHO~2~) (2), and Mn~3~(C~14~H~8~O~4~)~3~(C~4~H~9~NO)~4~ (3). Two of the syntheses gave multiphase products, but one resulted in a phase‐pure product 2. The crystal structures of 1 and 3 were solved by using conventional single‐crystal X‐ray diffraction, whereas the small crystal size of 2 made use of intense synchrotron radiation necessary. The crystal structure of 1 is composed of layers, which are only held together by van der Waals forces between the solvent of one layer and the framework of the adjacent layers, and the compound decomposes upon exposure to air. Structures 2 and 3 are 3D frameworks. Phase‐pure compound 2 does not contain the expected solvent diethylformamide, but formic acid residues. Measurements of magnetization and heat capacity data show that 2 is a metastable material with irreversible phase transitions at 6.5 or 4.5 K. In the metastable state, 2 is antiferromagnetic. Compound 3 has two types of pores along the b axis, and solvent molecules occupy the channels. Minor disorder of the solvent molecule is observed in one of the channels.