Synthesis and Characterization of a Two-Dimensional Zinc Phosphite, Zn3(tren)(HPO3)3·xH2O (x ≈ 0.5; tren = tris(2-aminoethyl)amine)

A comparison study of aliphatic and aromatic structure directing agents influencing the crystal and electronic structures, and properties of iodoplumbate hybrids: water induced structure conversion and visible light photocatalytic properties

The introduction of the aliphatic amines en (ethylenediamine), aep (N-(2-aminoethyl)piperazine) and tepa (tetraethylenepentamine), and the aromatic species 2,2'-bipy (2,2'-bipyridine) and dpe (1,2-di(4-pyridyl)ethylene) as structure directing agents (SDAs) into inorganic iodoplumbates affords six hybrids, namely [(Hen)4(H2.5O)2I](PbI6) (1), Cs2n[Pb3I8(en)2]n (2), (H3tepa)n(PbI5)n (3), (H2aep)n(PbI4)n (4), (Et22,2'-bipy)n(Pb2I6)n (5) and (Et2dpe)n(Pb2I6)n (6). 1 contains a discrete octahedral (PbI6)(4-) anion generated under the direction of a novel co-template, [(Hen)4(H2.5O)2I](4+). 2 contains inorganic Cs(+) ions and a novel hybrid anionic layer [Pb3I8(en)2]n(2n-) that has never been encountered in iodoplumbate hybrids. 3 features a zigzag (PbI5)(3-) chain with the charge being compensated by a triprotonated tepa cation. 4 is composed of perovskite sheets of lead(ii) octahedra and aep cations that are generated from tepa via an unprecedented in situ ligand reaction. Both 5 and 6 have (Pb2I6)n(2n-) chains and represent the first example of introducing a 2,2'-bipy or dpe derivative cation in iodoplumbate hybrids, respectively. The comparative study reveals that aliphatic amines and aromatic species contribute differently to the crystal and electronic structures, and the properties of the hybrids. Importantly, 1-4 exhibit interesting water induced structure conversions, while 5 and 6 can be used as heterogeneous photocatalysts for dye wastewater treatment under visible light irradiation.

Synthesis, structure, and polymorphism studies in amine-templated open-framework zinc phosphites

Five new zinc phosphites, [C10N4H26][Zn2(HPO3)4].2H2O, 1, [C10N4H26][Zn5(H2O)4(HPO3)6].4H2O, 2, [C10N4H26][Zn4(HPO3)6].2H2O, 3, [C10N4H26][Zn4(HPO3)6].2H2O, 4, and [Zn2(HPO3)2(C10N4H24)], 5, were synthesized employing solvo/hydrothermal reactions in the presence of 1,4-bis (3-aminopropyl) piperazine (APPIP). Single crystal X-ray diffraction studies indicate that all the compounds form a hierarchy of structures. While the structures 1 and 2 are low-dimensional, 3-5 have three-dimensional connectivity. ZnO4 and HPO3 units form a 4-membered ring and are connected through their corners forming a one-dimensional chain structure in 1. 2 has one-dimensional ladders connected by ZnO2(H2O)4 octahedral units forming a layer with 4- and 8-membered apertures. Compounds 3 and 4 have similar molecular formulae and connectivity, which makes them polymorphic in nature. The amine molecules exist in gauche and all-trans form in 3 and 4, respectively. The amine molecule binds with the zinc center in 5 and acts as a pillar between the two zinc phosphite layers. The present study outlines the possible role of synthesis parameters for the isolation of a number of different structures by employing a single amine molecule, APPIP. The observation of polymorphic structures along with the interconvertibilities of one of the phases is important and noteworthy. The 31P chemical shifts observed in NMR studies, consistent with the single crystal data, have been correlated with the valence sum values of the oxygen that are bound with the distinct phosphorus.