developing-photosensitizer-cobaloxime-hybrids-for-solar-driven-h2

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H<sub>2</sub> Production in Aqueous Aerobic Conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number ...

Indian Institute of Technology Gandhinagar

Guanine (G) quadruplexes (G4) are nucleic acid secondary structures formed by G-rich sequences, commonly found in human telomeric and oncogene-promoter regions, have emerged as targets for regulation of multiple biological processes. Considering their importance, targeting the G-quadruplex structure with small molecular binders is extremely pertinent. In this work, red emitting water soluble fluorophores bearing push-pull substituents were synthesized and examined for their interaction with human telomeric G4 and duplex (ds) -DNAs. The presence of a strong electron donating (dimethylamino) and electron withdrawing (cationic pyridinium) groups linked through a conjugated double bond helps in water solubility and enabling the emission in the near IR region (>700-nm). Binding of this cationic dye to the G4-DNA yields multiple-fold emission enhancement (~70 fold with G4-DNA vs. ~7 fold with ds-DNA) along with hypsochromic wavelength shifts (35 nm with G4-DNA and 8 nm with ds-DNA). The remarkable emission changes, ~2-4 fold enhanced binding efficiency noted with the antiparallel conformation of G4-DNA indicates preferential selectivity over ds-DNA. The molecular docking and dynamics studies of the ligands with duplex and G4-DNA were performed, and they provide insights into the mode of binding of these dyes with G4-DNA and supplement the experimental observations.

Cationic red emitting fluorophore: A light up NIR fluorescent probe for G4-DNA.

Metal nanomaterials have been reported as effective absorbents for the removal of pollutants in the water system, but the release of ions from these nanomaterials brings another concern. Herein, silver nanoclusters (AgNCs) were encapsulated in porous metal-organic frameworks of ZIF-8 (MOF-AgNCs). Compared to AgNCs, the release of Ag significantly decreases from MOF-AgNCs, indicating that the product presents a lower threat to the environment. The MOF-AgNCs were employed for the rapid removal of heavy metals, such as Pb and Mn, from water. The mechanism and removal efficiencies were investigated.

Silver Nanoclusters Encapsulated into Metal-Organic Frameworks for Rapid Removal of Heavy Metal Ions from Water.

White-light-emitting diodes are energy efficiency replacement of conventional lighting sources. Herein, we report the luminescent behavior of three simple cyanostilbenes with triphenylamine-donating groups bearing different electron-withdrawing groups (phenyl, pyridyl, and -nitrophenyl) in a common donor (D)-π-acceptor (A) α-cyanostilbene construct along with their thermal and electrochemical properties. The density functional theory (DFT) studies reveal that aggregation-induced emission characteristic feature of the D-π-A dyes is inversely proportional to the intramolecular charge transfer (ICT) effect, that is, phenyl-and pyridyl-substituted compounds show characteristic aggregation-induced emission in water, whereas the ICT effect is dominant for the nitro derivative. The extent of ICT and the solvatochromic emission shifts, from blue to red, depend on the strength of the electron-withdrawing group. White luminescence and tunable emission colors are obtained by careful admixtures of these cyanostilbenes bearing triphenylamines. The results rationalized through DFT and time-dependent DFT calculations follow a consistent trend with the energy levels measured from the electrochemical and optical studies. Thermogravimetric analysis and differential scanning calorimetry studies showed excellent thermal stability of the compounds. The scanning electron microscopy and dynamic light scattering measurements were performed to reveal the formation of aggregates. This strategy involving synthetically simple and structurally similar molecules with different emission properties has potential applications in the fabrication of multicolor and white-light-emitting materials.

Article	Year
Cationic red emitting fluorophore: A light up NIR fluorescent probe for G4-DNA. Journal of photochemistry and photobiology. B, Biology\| PubMed ID: 30529810	2019
Silver Nanoclusters Encapsulated into Metal-Organic Frameworks for Rapid Removal of Heavy Metal Ions from Water. Molecules (Basel, Switzerland)\| PubMed ID: 31277212	2019
Emission and Color Tuning of Cyanostilbenes and White Light Emission. ACS omega\| PubMed ID: 31458345	2018

Beena Kumari

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