Homochiral Metal–Organic Frameworks of Lead(II) and Cadmium(II) Constructed by Amino Acid-Functionalized Isophthalic Acids: Synthesis, Structure Diversity, and Optical Properties

On the basis of amino acid-functionalized isophthalic acids, four interesting homochiral metal–organic frameworks (HMOFs), namely, {[Pb2(HL1)2]·11H2O}n (1), {[Pb2(HL2)2]·12H2O}n (2), {[Cd6(L2)4(H2O)11]·6H2O}n (3), and [Pb(HL3)]n (4), were constructed (H3L1 = (S)-5-(((1-carboxyethyl)amino)methyl)isophthalic acid, H3L2 = (S)-5-(((1-carboxy-3-methylbutyl)amino)methyl)isophthalic acid, and H3L3 = (S)-5-(((1-carboxy-2-phenylethyl)amino)methyl)isophthalic acid). In 1, 2, and 4, all PbII ions have hemidirected coordination geometries despite the difference in coordination number, and ligands H3L1–H3L3 in negative bivalent zwitterionic forms adopt various coordination modes to bridge PbII centers into two- and three-dimensional (2D–3D) coordination polymers, respectively. Both 1 and 2 contain two independent 63-topological homochiral layers which further form a unique hydrogen-bonded double-layered HMOF with the stereochemically active lone pairs of all PbII ions pointing inward and the hydrophobic side arms of a...