A New Inorganic−Organic Hybrid Zinc Phosphate Prepared with l-Histidine with an Unusual Stability in Water

Abstract

A new layered zinc phosphate (Mu-39) has been synthesized by hydrothermal treatment with biomolecules as original templates. It was synthesized with the L-histidine amino acid (C 6 H 9 N 3 O 2 ). The structure was determined by a single crystal X-ray diffraction study combined with exhaustive solid-state NMR experiments. These last ones [ 1 H f 13 C HETCOR, 1 H single quantum/double quantum (DQ), 31 P, 1 H f 31 P CPMAS, 1 H f 31 P HETCOR] ascertained the formulation of Mu-39 as {[C 6 H 10 N 3 O 2 þ ][Zn 2 (HPO 4 )(PO 4 ) -] 3 H 2 O} n with a hydrogen phosphate and phosphate ligands, and ruled out partial protonation such as (H 1-x PO 4 )(H x PO 4 ). A 31 P magic angle spinning (MAS) NMR study supported the almost complete racemization of L-histidine during the hydrothermal synthesis with only a small enantiomeric excess of 25% remaining. The compound crystallizes in the triclinic symmetry (space group P1) with a = 8.6109(6) Å , b = 9.0319(6) Å , c = 9.9523(7) Å , and R = 84.481(2)°, β = 83.279(2)°, γ = 74.652(2)°, V = 739.56(9) Å 3 , Z = 2. The inorganic layer is built up from four-membered rings sharing T-O-T bonds (T = Zn and P) and connected to each other in order to form ladders which are joined together via a Zn-O-P bond for creating eight-membered rings. The interest and the originality of this new zinc phosphate come especially from its unusual stability in aqueous solution.

Syntheses and Crystal Structures of [M(H2O)6](C16H11O4SO3)2·2H2O (M= Zn, Mg, Co)

“…The packing of compounds 1 – 3 in Figure 2 illustrate the lamellar or layer‐like packing of hydrophobic and hydrophilic regions, which are similar to the packing of compounds cation 1,1′‐binaphthalene‐2,2′‐diyl phosphate salts and enantiopure trinuclear Cu‐amino alcoholate SBUs {Cu3(m‐L)4X2} 24,25. The charge‐assisted18–22 interactions and the intermolecular hydrogen bonds forms hydrophilic regions, and π–π stacking interactions between the isoflavone skeletons generate hydrophobic columns in the crystal structures of 1 – 3 .…”

“…In Figure 1, the sulfonato and carbonyl of the isoflvone skeletons, the two lattice water molecules and the six coordinated water molecules are linked by hydrogen bonds (Table 2). Atoms H8B, H10C from the coordinated water molecules O8 and O10, as donors with two oxygen atoms (O5, O6) from the sulfonato of isoflavone skeleton form charge‐assisted hydrogen bonds (aqua)O8–H8B ··· (–) O5(sulfonato) and (aqua)O10–H10C ··· (–) O6(sulfonato),18–22 they are important for the ligand orientation around the metal atom. A hydrogen bonding chain O8–H8C ··· O11 exists between the lattice water and the coordinated water molecules.…”

“…There are hydrogen bonds network in these areas (Figure 3). Apart from the hydrogen bonds involved in Figure 1 and Figure 2, the charge‐assisted18–22 hydrogen bonds (aqua)O10–H10B ··· (–) O6(sulfonato) (– x +2, – y , – z +1) exists between the coordinated and the sulfonato of the isoflavone skeleton. The charge‐assisted18–22 hydrogen bonds (aqua)O11–H11B ··· (–) O7(sulfonato) (– x +1, – y , – z ) exists between the sulfonato of the isoflavone skeleton and the lattice water molecule (Table 2).…”

Synthesis and structure of coordination polymers of praseodymium(III) and erbium(III) with hydrogen maleate and benzene-1,3-disulfonate as linkers

“…Water molecules serve as donors and negatively charged sulfonate and carboxylate groups serve as acceptors among these charge-assisted H-bonds. Such charge-assisted H-bonds are found to be stronger than H-bonds formed between neutral atoms and are known to play crucial role in supramolecular assemblies [46][47][48][49][50][51][52]. A strong intramolecular hydrogen bond is formed due to the hydrogen atom in hydrogen maleate anion (HMA) and because of this hydrogen bond the anion exists in a bent conformation making it topologically very similar to the disulfonate ligand.…”

Synthesis, crystal structures and supramolecular architectures of square pyramidal Cu(II) complexes containing aromatic chelating N,N’-donor ligands

“…The H-bonds to a charged carboxylate group or nitrate anion can be termed "charge-assisted H-bonds", here the carboxylate or nitrate groups as hydrogen bond acceptors carry negative ionic charges. Such charge-assisted H-bonds are much stronger than hydrogen bonds between neutral atoms [60][61][62][63][64][65][66][67]. Each of the monomer is connected to each other by (O1W-H2W…O6 X (symmetry code x = −x,-y,1-z hydrogen bonds) inbetween the coordinated apical nitrate anions and coordinated water molecules (Figure 5b).…”