Rationally designed and controlled syntheses of different series of 4d–4f heterometallic coordination frameworks based on lanthanide carboxylate and Ag(IN)2 substructures

Abstract

Different series of Ln(III)–Ag(I) heterometallic coordination frameworks, namely LnAg(OAc)(IN)₂(H₂O)·(ClO₄) [Ln = Tb (1a); Ho (1b), HOAc = acetic acid, HIN = isonicotinic acid], LnAg₂(OX)_0.5(IN)₃(H₂O)_1.5·(ClO₄) [Ln = Nd (2a); Eu (2b) Tb (2c), OX = oxalate], Eu₂Ag₃(OX)_0.5(IN)₆(NO₃)(ClO₄)(H₂O)₃·2(H₂O) (3), LnAg(OX) (IN)₂(H₂O) [Ln = Ce (4a); Sm (4b)], LnAg(Mal)(IN)₂(H₂O) [Ln = La (5a); Nd (5b), H₂Mal = malonic acid], Ln₃Ag₄(Lac)₂(IN)₈(H₂O)₅·2(ClO₄)·2.5(H₂O) [Ln = La (6a); Lu (6b), HLac = lactic acid], Sm₃Ag₄(Lac)₂(IN)₈(H₂O)₄·2(ClO₄)·2.5(H₂O) (7), and Eu₂Ag₃(S-Lac)(IN)₆(H2O)4·2(ClO₄)·4(H₂O) (8) were successfully synthesized by systematic variation of reaction parameters such as initial reactants, reaction time, pH, temperature, etc. Compounds 1a and 1b represent 3D coordination frameworks that are constructed from adjacent lanthanide carboxylate layers and pillared Ag(IN)₂ units. Compounds 2a, 2b and 2c comprise of 2D Ln-carboxylate-Ag layered networks and pillared Ag(IN)₂ units. Compound 3 exhibits 3D coordination frameworks that are built up from the assembly of europium-carboxylate layers and pillared Ag(IN)₂ units. 3D coordination networks of compounds 4a and 4b containing tetranuclear Ln₂Ag₂ cores are constructed from 2D cerium oxalate layers and tilted pillared Ag(IN)₂ subunits. Compounds 5a and 5b display attractive 3D coordination frameworks constructed of 2D lanthanum malonate chains and pillared Ag(IN)₂ units. Compounds 6a and 6b are 2D coordination frameworks comprised of 1D racemic lanthanum carboxylate chains and pillared Ag(IN)₂ units. The crystal structure of 7 is almost the same as that of 6a and 6b, only one less coordination water molecule is coordinated to its metal centre. Compound 8, which spontaneously resolved upon crystallization, represents the first example of a 3D Ln–Ag coordination framework built up from 1D europium-carboxylate chains containing chiral molecules and pillared Ag(IN)₂ units.