The dimeric unit [La(H 2O) 4( m-PO 3C 6H 4COOH)( m-PO 2(OH)C 6H 4COOH)( m-PO(OH) 2C 6H 4COOH)] 2 as building block of layered hybrid material

Abstract

A new hybrid organic–inorganic material with the structural formula unit [La(H 2O) 4( m-PO 3C 6H 4COOH)( m-PO 2(OH)C 6H 4COOH)( m-PO(OH) 2C 6H 4COOH)] 2 (or [La(H 2O) 4C 21H 18O 15P 3] 2) has been synthesized under hydrothermal condition from La(NO 3) 3·6H 2O and 3-phosphonobenzoic acid ( m-PO(OH) 2–C 6H 4–COOH) which is a rigid organic precursor possessing two types of functional groups: phosphonic acid and carboxylic acid. The two units of the produced hybrid are linked together by hydrogen bonds leading to a layered framework composing of by a repetition of inorganic and organic slices. The organic layers consist of dimeric units made of two meta-phosphono-benzoic acid linked together by hydrogen bonds involving their COOH groups. Two kinds of dimeric units are observed: PO 3C 6H 4COOH⋯HOOCC 6H 4PO(OH) 2, present 2 times in the structure, and PO 2(OH)C6H4COOH⋯HOOCC 6H 4PO 2(OH). The material crystallises in a monoclinic cell ( C2/ c (15) space group) with the following parameters: a = 42.515(4) Å, b = 7.4378(6) Å, c = 20.307(2) Å, β = 118.031(6)°, V = 5668.2(9) Å 3, Z = 4, density = 1.908 g/cm 3.