Кафедра биофизики

Fluorescent carbon dots (C-dots) are new class of nanomaterials with widespread applications in optoelectronics, bio-imaging, catalysis, and sensing. The origin of photoluminescence of carbon dots is a debatable issue which is pretend to depend on the chemical structures such as graphitic conjugated core, molecular fluorophores and the surface defect states found to be dependent on the method of preparation. In this review, we have illustrated the important issues and challenges of the luminescent carbon dots and their potential applications. Graphitic conjugated core containing carbon dots is being synthesized usually from bulk materials like graphite, graphene and graphene oxide which exhibit size dependent photoluminescence behaviour due to quantum confinement. On the other hand, carbon dots synthesized from small molecules exhibit excitation dependent emission due to the presence of surface energy trap states which can be tuned by surface modification. Again, presence of both conjugated core and surface defect generates dual emission property. It is evident that various molecular fluorophores are produced inside carbon dots during low temperature synthesis. Hetero-atom doping is another strategy to tune the photoluminescence properties of carbon dots. Red emitting carbon dots are found to be suitable for bio-imaging applications after surface modification. Again, high quantum yield and solar light absorbing carbon dots are required for light harvesting and optoelectronic applications. Surface modified carbon dots are found to be appropriate for sensing applications. Analysis reveals that carbon dots based hybrid systems provide good applicability towards construction of solar cell devices because of their efficient charge separation.

Chemical Structure monitors the photoluminescence properties of carbon dots

Recent years has witnessed increasing development and exploitation of fluorescence techniques which has been spurred by the discovery, design and synthesis of novel fluorescent molecules. In the realm of nucleic acids, both modest and dramatic structural modification of the nucleobase may engender it with fluorescence. This review focuses on the design, synthesis and applications of purine nucleoside analogs possessing fluorescently modified nucleobases, particularly for detection of nucleic acid sequences or for structural studies on nucleic acids. Thus, fluorescent nucleoside/nucleotide analogs that can be incorporated into oligonucleotides and report changes due to base-pairing/stacking or microenvironmental alterations, such as polarity changes in the grooves, are highlighted. Whenever available, the photophysical mechanism giving rise to the environmental responsiveness of the fluorescent nucleoside/tide is presented.

Energy shortages and global warming are two main problems the world is currently facing. Photocatalytic CO₂ reduction is one of the most promising solutions to the above issues. Among the various photocatalysts, faceted TiO₂ crystals have attracted wide attention due to their excellent photocatalytic performance for CO₂ reduction. This review encompasses the recent advances in the application of facet-engineered TiO₂-based catalysts for CO₂ photocatalytic reduction. The review begins with the fundamentals of CO₂ photocatalytic reduction over TiO₂. In the following section, we discuss the surface atom structure and electronic structure of faceted TiO₂ crystals and the related the CO₂/water adsorption and charge transfer/separation properties. Then, we outline the modification strategies for faceted TiO₂ and their influence on the CO₂ photocatalytic reduction performance. Finally, a summary and the future perspectives of facet-engineered TiO₂ photocatalysts for CO₂ photoreduction are presented.

For a long time, starting from pioneering works of M. Irie in the late 80 s and early 90 s of the last century, photochromic diarylethenes were primarily associated with dithienylethenes – diarylethenes possessing thiophene groups. However, about 10 years ago, azole heterocycles (thiazole, oxazole, imidazole) started to be used as aryl moieties instead of common thiophenes, which contributed significantly to the development of diarylethene-based photochromes. In this review, we analyzed in detail the effects of substituting traditional thiophenes in diarylethenes by azoles and revealed amazing examples of functional molecules, materials, and devices based on azole-containing photochromic molecules.

Highly anisotropic 2D nanosheets of inorganic solids with nanometer-level thickness attract a great deal of research activity because of their unique merits in exploring novel high performance photocatalysts applicable for environmental purification and production of renewable clean energy. The 2D inorganic nanosheets possess many valuable properties such as tailorable band structures and chemical compositions, large surface areas, well-defined defect-free surface structure, and tunable electrical conductivities. Due to these unique advantages of 2D inorganic nanosheets, these materials can be used as promising building blocks for hybrid-type photocatalysts with optimized band structures, expanded surface areas, improved charge separation behaviors, and enhanced reaction kinetics. Of prime importance is that unusually strong electronic coupling can occur between very thin 2D inorganic nanosheets and hybridized nanospecies, leading to the synergistic optimization of electronic and optical properties, and thus the remarkable enhancement of photocatalytic activity. Depending on the type of component nanosheets, diverse examples of inorganic nanosheet-based photocatalysts are presented along with the in-depth discussion about critical roles of inorganic nanosheet in these hybrid photocatalysts. Future perspectives in the researches for 2D inorganic nanosheet-based photocatalysts are discussed to offer useful directions for designing and synthesizing novel high performance photocatalysts applicable for renewable energy production and environmental purification.