A series of s-block (Ca, Sr and Ba) metal–organic frameworks: synthesis and structure–property correlation

摘要: A series of metal–organic frameworks based on alkaline earth metal ions (Ca, Sr and Ba) 1,3,5-benzenetribenzoic acid (BTB) have been synthesized characterized. These are [H2N(CH3)2][Ca7(BTB)5(H2O)8(DMF)4]·4H2O (1), [H2N(CH3)2]2[Sr5(H2O)6(BTB)4] (2) [H2N(CH3)2][Ba(H2O)(BTB)] (3). All the structures three-dimensional in nature with different secondary building units. Compound 1 contains one-dimensional Ca–O–Ca zigzag chains while compound 2 Sr5O28 pentameric clusters 3 Ba–O–Ba chains. Both compounds form (3,6)-net connectivity forms (3,12)-net connectivity. Optical band gap energy measurements show that (2.65 eV) has low compared to (3.22 (3.32 eV). This variation may be due difference structural arrangement. crystallizes a non-centrosymmetric space group (Pna21), which belongs polar point C2v. displays strong SHG response good ferroelectric piezoelectric properties.