A Cyclic Titanium-Oxo Cluster with a Tetrathiafulvalene Connector as a Precursor for Highly Efficient Adsorbent of Cationic Dyes

Abstract

Titanium-oxo clusters (TOCs) have been studied for applications in catalysis, energy storage and transfer, light emission, and so on; however, use of TOCs for the selective adsorption of dyes has not yet been reported. Herein, a TOC compound formulated as [Ti6O3(OiPr)14(TTFTC)]4 (1, TTFTC = tetrathiafulvalene-tetracarboxylate) was successfully prepared and crystallographically characterized. Compound 1 has a cyclic structure assembled by four Ti6 clusters and four rodlike TTFTC connectors. Red compound 1 self-condenses to form a black polymeric organic–inorganic hybrid material (denoted as B-1), which was characterized by various techniques. B-1 is an amorphous TiO material that is formed by the irregular condensation of 1 by the removal of alkoxyl groups. B-1 exhibits high dye adsorption efficiency toward cationic dyes with a q e value of 651.3 mg/g at 298 K for methylene blue (MB). Moreover, B-1 can be used to selectively remove MB not only from mixed cationic–anionic dye solutions but also from some mixed cationic dyes, which is related to their structures. Kinetic, isotherm, and thermodynamic studies demonstrated that the pseudo-second-order kinetic model and Freundlich model show a good fit to the experimental data. The adsorption process involves an exothermic and entropy decreasing process. In addition, dye-adsorbed B-1 can be further used as a photocurrent-responsive material. The work opens up a new field for the application of TOCs in the selective adsorption and removal of dyes.

Uncommon 3D Twofold Interpenetrated Zinc Phosphate Consisting of Inorganic Chains and Mixed Ligands for Highly Efficient Dye Removal Ability Using Its Nanosized Particles

“…So far, this is the first example of metal phosphate with an interpenetrating structure of twofold 3D framework that is built of 1D inorganic chains and organic linkers (nitrogen and oxygen donors), except one 2D/3D network comprises 4,4′-bipyridine molecules and isolated 0D nodes of nickel phosphate . Recent reports of crystalline materials have attracted a great deal of attention for the dye adsorption and removal from aqueous solutions . Interestingly, the title compound also exhibited the efficient capture property for EBT, EBA, and EBB organic dyes (1.0 × 10 –4 M) from aqueous solutions using its downsized particles (denoted as NTOU-8 nano ).…”

Topotactic Conversion of Titanium-Oxo Clusters to a Stable TOC-Based Metal–Organic Framework with the Selective Adsorption of Cationic Dyes

“…Herein, tetrathiafulvalene-tetracarboxylate (TTFTC) and phenanthroline (phen) were chosen as functional ligands to construct a new TOC. TTFTC was selected because of its ability to serve as a linker for constructing a cyclic structure and because of its key role in adsorption, 30 and the introduction of phen is anticipated to replace some isopropanol groups and modulate the configuration of TOCs. A rectangular ring TOC, formulated as [Ti 6 O 6 (O i Pr) 8 (TTFTC)(phen) 2 ] 2 •6THF•2CH 2 Cl 2 •2C 3 H 7 OH (1, TTFTC-Ti 12 , TTFTC = tetrathiafulvalene-tetracarboxylate, and phen = phenanthroline), was crystallographically characterized.…”

A Systematic Crystallographic Study of the Host–Guest Interactions between Amines and Ti8 Polyoxotitanium Clusters

“…In this study, we investigate the host–guest interactions between polyoxotitanium clusters (PTCs) and a series of amines by X-ray crystallography. The Ti–O–Ti moiety of PTCs resembling the C–O–C of crown ether is potential hydrogen bond (H-bond) acceptor. − In fact, cyclic PTCs have been exploited as hosts for alkyl ammonium cations, metal ions, and solvent molecules. − For example, a secondary ammonium cation [NH 2 Et 2 ] + was encapsulated in a ring-shaped Ti 8 cluster through N–H···O bonds . Fu and Wang reported, respectively, that linear and cyclic amines can be hosted by Ti 8 wheel clusters to form pseudo-rotaxane or catenane-like structures. , Winpenny and co-workers isolated a family of cyclic [Ti x O ( x +1) ] ( x = 7, 8, or 9) clusters.…”