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Indian Journal of Pharmacology 2017
Topics: Anti-Infective Agents; Humans; Light; Pharmacology; Photic Stimulation; Photochemistry; Photochemotherapy; Phototherapy
PubMed: 29033480
DOI: 10.4103/0253-7613.215730 -
Chemical Reviews Jun 2021The merging of click chemistry with discrete photochemical processes has led to the creation of a new class of click reactions, collectively known as photoclick... (Review)
Review
The merging of click chemistry with discrete photochemical processes has led to the creation of a new class of click reactions, collectively known as photoclick chemistry. These light-triggered click reactions allow the synthesis of diverse organic structures in a rapid and precise manner under mild conditions. Because light offers unparalleled spatiotemporal control over the generation of the reactive intermediates, photoclick chemistry has become an indispensable tool for a wide range of spatially addressable applications including surface functionalization, polymer conjugation and cross-linking, and biomolecular labeling in the native cellular environment. Over the past decade, a growing number of photoclick reactions have been developed, especially those based on the 1,3-dipolar cycloadditions and Diels-Alder reactions owing to their excellent reaction kinetics, selectivity, and biocompatibility. This review summarizes the recent advances in the development of photoclick reactions and their applications in chemical biology and materials science. A particular emphasis is placed on the historical contexts and mechanistic insights into each of the selected reactions. The in-depth discussion presented here should stimulate further development of the field, including the design of new photoactivation modalities, the continuous expansion of λ-orthogonal tandem photoclick chemistry, and the innovative use of these unique tools in bioconjugation and nanomaterial synthesis.
Topics: Click Chemistry; Cycloaddition Reaction; Imines; Nitriles; Photochemistry; Tetrazoles
PubMed: 33104332
DOI: 10.1021/acs.chemrev.0c00799 -
Protein Science : a Publication of the... Aug 2021Cryptochromes (CRYs) function as blue light photoreceptors in diverse physiological processes in nearly all kingdoms of life. Over the past several decades, they have... (Review)
Review
Cryptochromes (CRYs) function as blue light photoreceptors in diverse physiological processes in nearly all kingdoms of life. Over the past several decades, they have emerged as the most likely candidates for light-dependent magnetoreception in animals, however, a long history of conflicts between in vitro photochemistry and in vivo behavioral data complicate validation of CRYs as a magnetosensor. In this review, we highlight the origins of conflicts regarding CRY photochemistry and signal transduction, and identify recent data that provides clarity on potential mechanisms of signal transduction in magnetoreception. The review primarily focuses on examining differences in photochemistry and signal transduction in plant and animal CRYs, and identifies potential modes of convergent evolution within these independent lineages that may identify conserved signaling pathways.
Topics: Animals; Cryptochromes; Magnetic Phenomena; Models, Molecular; Photobiology; Photochemistry; Plants; Signal Transduction
PubMed: 33993574
DOI: 10.1002/pro.4124 -
The Journal of Organic Chemistry Mar 2023Monomers of benzimidazole trapped in an argon matrix at 15 K were characterized by vibrational spectroscopy and identified as 1-tautomers exclusively. The photochemistry...
Monomers of benzimidazole trapped in an argon matrix at 15 K were characterized by vibrational spectroscopy and identified as 1-tautomers exclusively. The photochemistry of matrix-isolated 1-benzimidazole was induced by excitations with a frequency-tunable narrowband UV light and followed spectroscopically. Hitherto unobserved photoproducts were identified as 4- and 6-tautomers. Simultaneously, a family of photoproducts bearing the isocyano moiety was identified. Thereby, the photochemistry of benzimidazole was hypothesized to follow two reaction pathways: the fixed-ring and the ring-opening isomerizations. The former reaction channel results in the cleavage of the NH bond and formation of a benzimidazolyl radical and an H-atom. The latter reaction channel involves the cleavage of the five-membered ring and concomitant shift of the H-atom from the CH bond of the imidazole moiety to the neighboring NH group, leading to 2-isocyanoaniline and subsequently to the isocyanoanilinyl radical. The mechanistic analysis of the observed photochemistry suggests that detached H-atoms, in both cases, recombine with the benzimidazolyl or isocyanoanilinyl radicals, predominantly at the positions with the largest spin density (revealed using the natural bond analysis computations). The photochemistry of benzimidazole therefore occupies an intermediate position between the earlier studied prototype cases of indole and benzoxazole, which exhibit exclusively the fixed-ring and the ring-opening photochemistries, respectively.
PubMed: 36795993
DOI: 10.1021/acs.joc.2c02560 -
Chemical Reviews Jun 2021At its basic conceptualization, photoclick chemistry embodies a collection of click reactions that are performed via the application of light. The emergence of this... (Review)
Review
At its basic conceptualization, photoclick chemistry embodies a collection of click reactions that are performed via the application of light. The emergence of this concept has had diverse impact over a broad range of chemical and biological research due to the spatiotemporal control, high selectivity, and excellent product yields afforded by the combination of light and click chemistry. While the reactions designated as "photoclick" have many important features in common, each has its own particular combination of advantages and shortcomings. A more extensive realization of the potential of this chemistry requires a broader understanding of the physical and chemical characteristics of the specific reactions. This review discusses the features of the most frequently employed photoclick reactions reported in the literature: photomediated azide-alkyne cycloadditions, other 1,3-dipolarcycloadditions, Diels-Alder and inverse electron demand Diels-Alder additions, radical alternating addition chain transfer additions, and nucleophilic additions. Applications of these reactions in a variety of chemical syntheses, materials chemistry, and biological contexts are surveyed, with particular attention paid to the respective strengths and limitations of each reaction and how that reaction benefits from its combination with light. Finally, challenges to broader employment of these reactions are discussed, along with strategies and opportunities to mitigate such obstacles.
Topics: Alkynes; Azides; Click Chemistry; Cycloaddition Reaction; Photochemistry
PubMed: 33835796
DOI: 10.1021/acs.chemrev.0c01212 -
Molecules (Basel, Switzerland) Nov 2022A series of symmetrical dibenzylidene derivatives of cyclobutanone were synthesized with the goal of studying the physicochemical properties of cross-conjugated dienones...
A series of symmetrical dibenzylidene derivatives of cyclobutanone were synthesized with the goal of studying the physicochemical properties of cross-conjugated dienones (ketocyanine dyes). The structures of the products were established and studied by X-ray diffraction and by NMR and electronic spectroscopy. All the products had ,-geometry. The oxidation and reduction potentials of the dienones were determined by cyclic voltammetry. The potentials were shown to depend on the nature, position, and number of substituents in the benzene rings. A linear correlation was found between the difference of the electrochemical oxidation and reduction potentials and the energy of the long-wavelength absorption maximum. This correlation can be employed to analyze the properties of other compounds of this type. Quantum chemistry was used to explain the observed regularities in the electrochemistry, absorption, and fluorescence of the dyes. The results are in good agreement with the experimental redox potentials and spectroscopy data.
Topics: Photochemistry; Electrochemistry; Oxidation-Reduction; Magnetic Resonance Spectroscopy; Coloring Agents
PubMed: 36364429
DOI: 10.3390/molecules27217602 -
Biochemistry. Biokhimiia Oct 2023The diversity of the retinal-containing proteins (rhodopsins) in nature is extremely large. Fundamental similarity of the structure and photochemical properties unites... (Review)
Review
The diversity of the retinal-containing proteins (rhodopsins) in nature is extremely large. Fundamental similarity of the structure and photochemical properties unites them into one family. However, there is still a debate about the origin of retinal-containing proteins: divergent or convergent evolution? In this review, based on the results of our own and literature data, a comparative analysis of the similarities and differences in the photoconversion of the rhodopsin of types I and II is carried out. The results of experimental studies of the forward and reverse photoreactions of the bacteriorhodopsin (type I) and visual rhodopsin (type II) rhodopsins in the femto- and picosecond time scale, photo-reversible reaction of the octopus rhodopsin (type II), photovoltaic reactions, as well as quantum chemical calculations of the forward photoreactions of bacteriorhodopsin and visual rhodopsin are presented. The issue of probable convergent evolution of type I and type II rhodopsins is discussed.
Topics: Rhodopsin; Bacteriorhodopsins; Photochemistry
PubMed: 38105022
DOI: 10.1134/S0006297923100097 -
Geochemical Transactions 2017The participation of sunlight in the natural chemistry of the earth is presented as a unique field of study, from historical observations to prospects for future... (Review)
Review
The participation of sunlight in the natural chemistry of the earth is presented as a unique field of study, from historical observations to prospects for future inquiry. A compilation of known reactions shows the extent of light-driven interactions between naturally occurring components of land, air, and water, and provides the backdrop for an outline of the mechanisms of these phenomena. Catalyzed reactions, uncatalyzed reactions, direct processes, and indirect processes all operate in natural photochemical transformations, many of which are analogous to well-known biological reactions. By overlaying photochemistry and surface geochemistry, complementary approaches can be adopted to identify natural photochemical reactions and discern their significance in the environment.
PubMed: 28246525
DOI: 10.1186/s12932-017-0039-y -
Chemistry (Weinheim An Der Bergstrasse,... Nov 2021Melanin-like nanomaterials have found application in a large variety of high economic and social impact fields as medicine, energy conversion and storage, photothermal... (Review)
Review
Melanin-like nanomaterials have found application in a large variety of high economic and social impact fields as medicine, energy conversion and storage, photothermal catalysis and environmental remediation. These materials have been used mostly for their optical and electronic properties, but also for their high biocompatibility and simplicity and versatility of preparation. Beside this, their chemistry is complex and it yields structures with different molecular weight and composition ranging from oligomers, to polymers as well as nanoparticles (NP). The comprehension of the correlation of the different compositions and morphologies to the optical properties of melanin is still incomplete and challenging, even if it is fundamental also from a technological point of view. In this minireview we focus on scientific papers, mostly recent ones, that indeed examine the link between composition and structural feature and photophysical and photochemical properties proposing this approach as a general one for future research.
Topics: Melanins; Nanoparticles; Nanostructures; Photochemistry; Polymers
PubMed: 34505731
DOI: 10.1002/chem.202102479 -
Molecules (Basel, Switzerland) May 2023Cholesta-5,7,9(11)-trien-3β-ol (9,11-dehydroprovitamin D, CTL) is used as a fluorescent probe to track the presence and migration of cholesterol in vivo. We recently...
Cholesta-5,7,9(11)-trien-3β-ol (9,11-dehydroprovitamin D, CTL) is used as a fluorescent probe to track the presence and migration of cholesterol in vivo. We recently described the photochemistry and photophysics of CTL in degassed and air-saturated tetrahydrofuran (THF) solution, an aprotic solvent. The zwitterionic nature of the singlet excited state, CTL* is revealed in ethanol, a protic solvent. In ethanol, the products observed in THF are accompanied by ether photoadducts and by photoreduction of the triene moiety to four dienes, including provitamin D. The major diene retains the conjugated --diene chromophore and the minor is unconjugated, involving 1,4-addition of H at the 7 and 11 positions. In the presence of air, peroxide formation is a major reaction channel as in THF. X-ray crystallography confirmed the identification of two of the new diene products as well as of a peroxide rearrangement product.
PubMed: 37241827
DOI: 10.3390/molecules28104086