Heavy-Metal Ions Removal and Iodine Capture by Terpyridine Covalent Organic Frameworks

Porous materials are excellent candidates for water remediation in environmental issues. However, it is still a key challenge to design efficient adsorbents for rapid water purification from various heavy metal ions-contaminated wastewater in one step. Here, two robust nitrogen-rich covalent organic frameworks (COFs) bearing terpyridine units on the pore walls by a "bottom-up" strategy are reported. Benefitting from the strong chelation interaction between the terpyridine units and various heavy metal ions, these two terpyridine COFs show excellent removal efficiency and capability for Pb2+, Hg2+, Cu2+, Ag+, Cd2+, Ni2+, and Cr3+ from water. These COFs are shown to remove such heavy metal ions with >90% of contents at one time after the aqueous metal ions mixture is passed through the COF filter. The nitrogen-rich features of the COFs also endow them with the capability of capturing iodine vapors, offering the terpyridine COFs the potential for environmental remediation applications.

Synthesis and Characterization of Metallo-Supramolecular Polymers Based on Benzodipyrrolidone

A simple route to the preparation of benzodipyrrolidone (BDP) based monomeric building blocks containing 2,2':6',2″-terpyridines is reported from a common precursor 4'-(4-pinacolatoboronphenyl)-2,2':6',2″-terpyridine via Suzuki coupling reaction. Self-assembly polymerization with ruthenium (II) ions under mild conditions yielded a series of novel metallo-supramolecular polymers with weak donor-acceptor (D-A) structures based on benzodipyrrolidone. The structure of the bridge connected BDP with terpyridine have a significant impact on the wavelength and intensity of the intramolecular charge transfer (ICT) absorption peak. The resulting metallo-polymers exhibited strong double absorption bands around 315 nm and 510 nm involved in π-π* transitions and ICT or metal to ligand charge transfer (MLCT) absorption bands. The forming of D-A structure and coordination with ruthenium (II) ions is favorable to narrow the energy gap and the energy gaps of the resulting metallo-supramolecular polymers are 2.01 and 1.62 eV, respectively.

Synthesis of Bis-Terpyridine-Based Metallopolymers and the Thermoelectric Properties of Their Single Walled Carbon Nanotube Composites

Although the organic and the conventional inorganic thermoelectric (TE) materials have been extensively developed in recent years, the number of cases involving conducting metallopolymers is still quite limited. In view of the versatile coordination capability of the terpyridine fraction and the electron-rich nature of the 3,4-ethylenedioxythiophene moiety, a bis-terpyridine-featured ligand was designed, and a series of metallopolymers were then synthesized. Upon the addition of single-walled carbon nanotube (SWCNT), the TE properties of the resulting metallopolymer-SWCNT composite films were investigated. It was found that metal centres played an important role in affecting the morphology of the thin films, which was a key factor that determined the TE performances of the composites. Additionally, the energy levels of the metallopolymers were feasibly tuned by selecting different metal centres. With the combined effects of a uniform and condensed surface and an optimized band structure, the highest power factor was achieved by the Cu(II)-containing metallopolymer-SWCNT composite at the doping ratio of 75%, which reached 38.3 μW·m-1·K-2.

Terpyridine-Containing π-Conjugated Polymers for Light-Emitting and Photovoltaic Materials

2,2':6',2″-Terpyridine (tpy) is a versatile moiety used in the construction of small novel molecules or polymers. Extending or coupling tpy with π-conjugation structures can result in interesting optoelectronic properties. This mini-review summarizes the significant progress made over the past decades in the study of tpy-containing π-conjugated polymers and their application in light-emitting and photovoltaic materials. When coordinated with metal ions, tpy exhibits immense potential for the synthesis of metallo-supramolecular or metallo-polymer materials. Therefore, tpy-based metallo-polymers are the primary focus of this study. Selected examples will be reviewed with a special emphasis on the properties of these functional systems, which can consequently help further their application in light-to-electricity or electricity-to-light conversion fields.

Synthesis and characterization of metallo-supramolecular polymers

The incorporation of metal centers into the backbone of polymers has led to the development of a broad range of organometallic and coordination compounds featuring properties that are relevant for potential applications in diverse areas of research, ranging from energy storage/conversion to bioactive or self-healing materials. In this review, the basic concepts and synthetic strategies leading to these types of materials as well as the scope of available characterization techniques will be summarized and discussed.

Alcohol- and water-soluble bis(tpy)quaterthiophenes with phosphonium side groups: new conjugated units for metallo-supramolecular polymers

Bis(tpy)quaterthiophenes with symmetrically distributed two and four 6-bromohexyl side groups were prepared and modified by the reaction with triethylphosphine to give the corresponding ionic species. Both ionic and non-ionic bis(tpy)quaterthiophenes (unimers) were assembled with Zn(2+) and Fe(2+) ions to conjugated metallo-supramolecular polymers (MSPs), of which the ionic ones are soluble in alcohols and those derived from tetrasubstituted unimers are soluble even in water. The differences in assembly are specified between systems with (i) ionic and non-ionic unimers, (ii) Zn(2+) and Fe(2+) ion couplers, and (iii) methanol and water solvents. A substantial decrease in the stability of Fe-MSPs and a surprisingly high red shift of the luminescence band of Zn-MSPs were observed on going from methanol to aqueous solutions.

Effect of a three-dimensional hyperbranched structure on the ionic conduction of metallo-supramolecular polymers

3D metallo-supramolecular polymers exhibited 10–100 times higher ionic conductivity than their 1D equivalents due to the improved ion conduction pathway.

Alcohol-soluble bis(tpy)thiophenes: new building units for constitutional dynamic conjugated polyelectrolytes

Constitutional dynamics and spectral properties of conjugated ionic unimers and their metallo-supramolecular dynamers with Zn(ii) and Fe(ii) ion couplers are presented together with new knowledge on the MLCT band of bis(tpy)Fe(ii) units.

Novel metallo-dendrimers containing various Ru core ligands and dendritic thiophene arms for photovoltaic applications

A polymer solar cell device containing an active layer of BTRu2G3 : PC70BM = 1 : 3 (by wt), i.e., the third generation of the bis-Ru-based dendritic complex BTRu2G3 showed the highest PCE value of 0.77%.

Ruthenium(II)-bis(4′-(4-ethynylphenyl)-2,2′:6′, 2″-terpyridine) — A versatile synthon in supramolecular chemistry. Synthesis and characterization

A homoleptic ethynyl-substituted ruthenium(II)-bisterpyridine complex representing a versatile synthon in supramolecular chemistry was synthesized and analyzed by NMR spectroscopy, mass spectrometry and X-ray diffractometry. Furthermore, its photophysical properties were detailed by UV/Vis absorption, emission and resonance Raman spectroscopy. In order to place the results obtained in the context of the vast family of ruthenium coordination compounds, two structurally related complexes were investigated accordingly. These reference compounds bear either no or an increased chromophore in the 4′-position. The spectroscopic investigations reveal a systematic bathochromic shift of the absorption and emission maximum upon increasing chromophore size. This bathochromic shift of the steady state spectra occurs hand in hand with increasing resonance Raman intensities upon excitation of the metal-to-ligand charge-transfer transition. The latter feature is accompanied by an increased excitation delocalization over the chromophore in the 4′-position of the terpyridine. Thus, the results presented allow for a detailed investigation of the electronic effects of the ethynyl substituent on the metal-to-ligand charge-transfer states in the synthon for click reactions leading to coordination polymers.