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AIP Conference Proceedings [Author(s) THE 3RD INTERNATIONAL SEMINAR ON CHEMISTRY: Green Chemistry and its Role for Sustainability - Surabaya, Indonesia (18–19 July 2018)] - Green synthesis of silver nanoparticles using photo-induced reduction method
摘要： Silver Nanoparticles (AgNPs) has been successfully synthetized in this study using photoinduced reduction method with monochromatic light. In this method we use sodium citrate as capping agent without additional reducing agent. Silver nanoparticles characterized using Ultraviolet-Visible Spectroscopy (UV-Vis) and X-ray Diffraction (XRD). The synthetized AgNPs show that wavelength of light can affect the properties of AgNPs based on absorption spectra of UV-Vis. XRD measurement showed the characteristic peak of silver at 2θ of 38.060, 44.140, 64.470, and 77.400.
关键词： Photochemistry,Reduction,Sodium Citrate,AgNPs,Monochromatic light
更新于2025-09-23 15:23:52
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Controlling Chain Coupling and Single Chain Ligation by Two Colours of Visible Light
摘要： While photochemical synthesis offers access to spatiotemporal reaction control, its potential to selectively address specific reactions by the colour of light is usually limited by ubiquitous spectral absorption overlaps of the reactive groups. Inhere, a new concept is introduced that actively suppresses one ligation reaction by triggering the cycloreversion of the [2+2] cycloaddition of styrylpyrene. Combination of the photoreversible styrylpyrene chemistry with the [4+4] cycloaddition of 9-triazolylanthracene allows to initially induce chain coupling using UV light and to subsequently ligate the formed single chain nanoparticle (SCNP) with a second polymer chain using blue light. Seizing upon the first sequence independent λ-orthogonal reactivity established in here, the same macromolecular architecture was obtained in reverse irradiation sequence, by blue and subsequent violet light irradiation – completely foregoing high energy UV-light.
关键词： Polymer Ligation,Orthogonal Reactions,RAFT polymerization,Photochemistry,Single Chain Nanoparticles
更新于2025-09-23 15:23:52
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Primary and secondary photochemical transformations of biologically active precursor - Nitro-Nitrosyl ruthenium complex
摘要： Photolysis of [Ru(II)NOPy2(NO2)2OH] (A) complex was studied under blue light (445 nm) irradiation. The primary photo-process results in the formation of nitric oxide (NO) and a paramagnetic RuIII compound, the latter was detected by EPR technique. The quantum yield (6–11%) of primary photolytic process was determined from the evolution of UV–vis spectra in different solvents (water, ethanol, dimethyl sulfoxide and acetonitrile). The secondary processes compete with the NO-release and lead to a variety of ruthenium forms including new nitrosyl forms. Namely, processes of hydroxyl protonation, pyridine photocleavage and nitro – nitrito bond isomerization take a place. HPLC combined with IR and 15N – NMR spectroscopies clarified the composition of the new forms and their transformations during the photolysis. Supporting EPR and IR DFT calculations confirmed the structure of photoproducts. The oxidation of NO in the secondary processes significantly influences on the total amount of nitric oxide release and reaction routes.
关键词： Nitrosyl ruthenium,Photocleavage,Photochemistry,Nitric oxide release
更新于2025-09-23 15:23:52
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<i>N</i> -Arylphenothiazines as strong donors for photoredox catalysis – pushing the frontiers of nucleophilic addition of alcohols to alkenes
摘要： A new range of N-phenylphenothiazine derivatives was synthesized as potential photoredox catalysts to broaden the substrate scope for the nucleophilic addition of methanol to styrenes through photoredox catalysis. These N-phenylphenothiazines differ by their electron-donating and electron-withdrawing substituents at the phenyl group, covering both, σ and π-type groups, in order to modulate their absorbance and electrochemical characteristics. Among the synthesized compounds, alkylaminylated N-phenylphenothiazines were identified to be highly suitable for photoredox catalysis. The dialkylamino substituents of these N-phenylphenothiazines shift the estimated excited state reduction potential up to ?3.0 V (vs SCE). These highly reducing properties allow the addition of methanol to α-methylstyrene as less-activated substrate for this type of reaction. Without the help of an additive, the reaction conditions were optimized to achieve a quantitative yield for the Markovnikov-type addition product after 20 h of irradiation.
关键词： redox potential,photochemistry,addition,photoredox catalysis,phenothiazine
更新于2025-09-23 15:22:29
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Separation of Spectroscopically Uniform Nanographenes
摘要： Excitation-dependent photoluminescence (PL) is a well-known property of graphene quantum dots (GQDs). For the development of carbon-based photofunctional materials, GQDs possessing uniform PL properties are in high demand. A protocol has been established to separate spectroscopically uniform lipophilic GQD-1 a from a mixture of GQD-1 mainly composed of GQD-1 a and GQD-1 b. The mixture of GQD-1 was synthesized through the reaction of p-methoxybenzylamine with GQD-2 prepared from graphite by common oxidative exfoliation. Size-exclusion chromatography gave rise to GQD-1 a and GQD-1 b, with diameters of 19.8 and 4.9 nm, respectively. Large GQD-1 a showed that the PL was fairly independent of the excitation wavelengths, whereas the PL of small GQD-1 b was dependent on excitation. The excitation-dependent nature is most likely to be associated with the structures of sp2 domains on the graphene surfaces. The large sp2-conjugated surface of GQD-1 a is likely to possess well-developed and large sp2 domains, the band gaps of which do not significantly vary. The small sp2-conjugated surface of GQD-1 b produces small sp2-conjugated domains that generate band gaps differing with domain sizes.
关键词： photochemistry,luminescence,quantum dots,graphene,chromatographic separation
更新于2025-09-23 15:22:29
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A Self-Reporting Photocatalyst for Online Fluorescence Monitoring of High Throughput RAFT Polymerization
摘要： Translating controlled/living radical polymerization (CLRP) from batch to the high throughput production of polymer libraries presents several challenges in terms of both polymer synthesis and characterization. Although recently there have been significant advances in the field of low volume, high throughput CLRP, techniques able to simultaneously monitor multiple polymerizations in an 'online' manner have not yet been developed. Here, we report our discovery that 5,10,15,20-tetraphenyl-21H,23H-porphine zinc (ZnTPP) is a self-reporting photocatalyst that can mediate PET-RAFT polymerization as well as report on monomer conversion via changes in its fluorescence properties. This enables the use of a microplate reader to conduct high throughput 'online' monitoring of PET-RAFT polymerizations performed directly in 384-well, low volume microtiter plates.
关键词： photochemistry,polymerization,online monitoring,PET-RAFT
更新于2025-09-23 15:22:29
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Enantioselective Visible Light-mediated Formation of 3-Cyclopropylquinolones via Triplet-sensitized Deracemization
摘要： 3-Allyl-substituted quinolones undergo a triplet-sensitized di-π-methane rearrangement to the corresponding 3-cyclopropylquinolones upon irradiation with visible light (λ = 420 nm). A chiral hydrogen bonding sensitizer (10 mol%) was shown to promote the reaction enantioselectively (88-96% yield, 32-55% ee). Surprisingly, it was found that the enantiodifferentiation does not occur at the state of initial product formation but that it is the result of a deracemization event. The individual parameters that control the distribution of enantiomers in the photostationary state have been identified.
关键词： enantioselectivity,small ring systems,photochemistry,hydrogen bonds,sensitizers,chiral resolution
更新于2025-09-23 15:22:29
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Photonics of boron(III) and zinc(II) dipyrromethenates as active media for modern optical devices
摘要： Photonics of complexes of p- and d-elements with dipyrromethenates is investigated. The role of substituents (their type and localization in the ligand) and of the medium in which dipyrromethenates are placed (solvents, gas mixtures, or solid matrices) is discussed as well as the effect of complexing agents on photonics of the examined complexes. The possibilities for dipyrromethenates application as liquid and solid state laser active media, sensor media for determining the oxygen concentration in a gas mixture, and photosensitizers for singlet oxygen generation in optical devices are presented.
关键词： Photochemistry,Dipyrromethenates,Sensorics,Photophysics,Lasing,Photosensitization
更新于2025-09-23 15:22:29
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Light-powered, artificial molecular pumps: a minimalistic approach
摘要： The realization of artificial molecular motors capable of converting energy into mechanical work is a fascinating challenge of nanotechnology and requires reactive systems that can operate away from chemical equilibrium. This article describes the design and construction of a simple, supramolecular ensemble in which light irradiation causes the directional transit of a macrocycle along a nonsymmetric molecular axle, thus forming the basis for the development of artificial molecular pumps.
关键词： molecular machine,azobenzene,rotaxane,supramolecular chemistry,photochemistry
更新于2025-09-23 15:22:29
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Fine-Tuning Aromatic Stacking and Single-Crystal Photoluminescence through Coordination Chemistry
摘要： Organic aromatics usually show a decrease in fluorescence efficiency in the solid state on account of well-known aggregation induced quenching. We have found that single crystals of coordination polymers consisting of γ-aminobutyric acid functionalized naphthalenediimide ligand (H2GABA-NDI) can give rise to highly emissive, broad, and red-shifted photoluminescence (PL) in the solid state. To better understand the origin of the bandwidth broadening with the π–π stacking distances, we performed time-resolved PL studies in a series of polymers with a variety of metal centers. We conclude that the broad steady-state PL signals is originated from a superposition of two emissive states with differing energy and lifetimes, with the lower energy one produced by the interchromophoric interactions mediated by π–π stacking of neighboring NDI units. Our work demonstrates that coordination chemistry is an effective tool to modulate interchromophoric couplings and that simple PL analysis can be used as a measure of the degree of π-stacking.
关键词： crystal engineering,luminescence,photochemistry,stacking interactions,coordination modes
更新于2025-09-23 15:22:29