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We simulate the photodynamics of gas-phase cyclobutanone excited to the S2 state using fewest switches surface hopping (FSSH) dynamics powered by time-dependent density functional theory (TDDFT). We predict a total photoproduct yield of 8%, with a C3:C2 product ratio of 0 trajectories to 8 trajectories. One primary S2 → S1 conical intersection is identified involving the compression of an α-carbon–carbon–hydrogen bond angle. Excited state lifetimes computed with respect to electronic state populations were found to be 3.96 ps (S2 → S1) and 498 fs (S1 → S0). We also generate time-resolved difference pair distribution functions (ΔPDFs) from our TDDFT-FSSH dynamics results in order to generate direct comparisons with ultrafast electron diffraction experiment observables. Global and target analysis of time-resolved ΔPDFs produced a distinct set of lifetimes: (i) a 0.548 ps decay and (ii) a 1.69 ps decay, both resembling the S2 minimum, as well as (iii) a long decay that resembles the S1 minimum geometry and the fully separated C2 products. Finally, we contextualize our results by considering the impact of the most likely sources of significant errors. [ABSTRACT FROM AUTHOR]

Understanding the nonadiabatic dynamics of complex systems is a challenging task in computational photochemistry. Herein, we present an efficient and user-friendly quantum mechanics/molecular mechanics (QM/MM) interface to run on-the-fly nonadiabatic dynamics. Currently, this interface consists of an independent set of codes designed for general-purpose use. Herein, we demonstrate the ability and feasibility of the QM/MM interface by integrating it with our long-term developed JADE package. Tailored to handle nonadiabatic processes in various complex systems, especially condensed phases and protein environments, we delve into the theories, implementations, and applications of on-the-fly QM/MM nonadiabatic dynamics. The QM/MM approach is established within the framework of the additive QM/MM scheme, employing electrostatic embedding, link-atom inclusion, and charge-redistribution schemes to treat the QM/MM boundary. Trajectory surface-hopping dynamics are facilitated using the fewest switches algorithm, encompassing classical and quantum treatments for nuclear and electronic motions, respectively. Finally, we report simulations of nonadiabatic dynamics for two typical systems: azomethane in water and the retinal chromophore PSB3 in a protein environment. Our results not only illustrate the power of the QM/MM program but also reveal the important roles of environmental factors in nonadiabatic processes. [ABSTRACT FROM AUTHOR]

This study was focused on the photochemistry of OAlOH and three possible pathways, which were studied with high-level multireference configuration interaction ab initio calculations. We computed cuts of the six-dimensional potential energy surfaces for the ground, the lowest singlet and triplet excited states, and probed the photodissociation mechanisms and the stabilities. The OAlOH electronic spectrum, with an energy reaching 7.15 eV, contained four prominent peaks. Photodissociation to AlO, OH, and AlOH constituted a plausible mechanism within the deep-UV range (λ = 250.4 nm). Our data indicated the photostability of OAlOH in the near-UV‒Vis region, so detection with laser-induced fluorescence is possible. Fluorescence and phosphorescence may occur upon excitation at 363.5 nm. The roles of OAlOH in the photochemical reactions of Al-bearing molecules in the upper atmosphere and VY Canis Majoris are discussed. [ABSTRACT FROM AUTHOR]

Click chemistry refers to selective reactions developed for grafting of bio(macro)molecules in their biological media. Caged click compounds have been employed to spatiotemporally control click reactions. Here, we survey the uncaging of photo-dibenzocyclooctyne-OH (photoDIBO-OH) to its click-chemistry active form DIBO-OH, with particular attention to its conversion timescale and efficiency. Ultraviolet pump–infrared probe experiments reveal a stepwise decarbonylation: first, carbon monoxide (C≡O) is released within 1.8 ps, and then, it converts, within 10 ps, to DIBO-OH. Completion of uncaging is achieved with an efficiency of ∼50%. A successful demonstration of two-photon uncaging of photoDIBO-OH at long wavelength (700 nm) confers enhanced in vivo compatibility and proceeds on the same timescale. [ABSTRACT FROM AUTHOR]

We study the ultrafast time evolution of cyclobutanone excited to the singlet n → Rydberg state through non-adiabatic surface-hopping simulationsperformed at extended multi-state complete active space second-order perturbation (XMS-CASPT2) level of theory. These dynamics predict relaxation to the ground-state with a timescale of 822 ± 45 fs with minimal involvement of the triplets. The major relaxation path to the ground-state involves a three-state degeneracy region and leads to a variety of fragmented photoproducts. We simulate the resulting time-resolved electron-diffraction spectra, which track the relaxation of the excited state and the formation of various photoproducts in the ground state. [ABSTRACT FROM AUTHOR]

Owing to ring strain, cyclic ketones exhibit complex excited state dynamics with multiple competing photochemical channels active on the ultrafast timescale. While the excited state dynamics of cyclobutanone after π* ← n excitation into the lowest-energy excited singlet (S1) state has been extensively studied, the dynamics following 3s ← n excitation into the higher-lying singlet Rydberg (S2) state are less well understood. Herein, we employ fully quantum multiconfigurational time-dependent Hartree (MCTDH) simulations using a model Hamiltonian as well as "on-the-fly" trajectory-based surface-hopping dynamics (TSHD) simulations to study the relaxation dynamics of cyclobutanone following 3s ← n excitation and to predict the ultrafast electron diffraction scattering signature of these relaxation dynamics. Our MCTDH and TSHD simulations indicate that relaxation from the initially-populated singlet Rydberg (S2) state occurs on the timescale of a few hundreds of femtoseconds to a picosecond, consistent with the symmetry-forbidden nature of the state-to-state transition involved. There is no obvious involvement of excited triplet states within the timeframe of our simulations (<2 ps). After non-radiative relaxation to the electronic ground state (S0), vibrationally hot cyclobutanone has sufficient internal energy to form multiple fragmented products including C2H4 + CH2CO (C2; 20%) and C3H6 + CO (C3; 2.5%). We discuss the limitations of our MCTDH and TSHD simulations, how these may influence the excited state dynamics we observe, and—ultimately—the predictive power of the simulated experimental observable. [ABSTRACT FROM AUTHOR]

The ability to study chemical dynamics on ultrafast timescales has greatly advanced with the introduction of X-ray free electron lasers (XFELs) providing short pulses of intense X-rays tailored to probe atomic structure and electronic configuration. Fully exploiting the full potential of XFELs requires specialized experimental endstations along with the development of techniques and methods to successfully carry out experiments. The liquid jet endstation (LJE) at the Linac Coherent Light Source (LCLS) has been developed to study photochemistry and biochemistry in solution systems using a combination of X-ray solution scattering (XSS), X-ray absorption spectroscopy (XAS), and X-ray emission spectroscopy (XES). The pump-probe setup utilizes an optical laser to excite the sample, which is subsequently probed by a hard X-ray pulse to resolve structural and electronic dynamics at their intrinsic femtosecond timescales. The LJE ensures reliable sample delivery to the X-ray interaction point via various liquid jets, enabling rapid replenishment of thin samples with millimolar concentrations and low sample volumes at the 120 Hz repetition rate of the LCLS beam. This paper provides a detailed description of the LJE design and of the techniques it enables, with an emphasis on the diagnostics required for real-time monitoring of the liquid jet and on the spatiotemporal overlap methods used to optimize the signal. Additionally, various scientific examples are discussed, highlighting the versatility of the LJE.

BiOCl micro/nanoplates and their hierarchical architectures were selectively synthesized via 24 h of hydrothermal reaction at 180 °C and a wide range of solution pH (2–12), where the vital role of solution pH in phase/morphology evolution were elaborated from solution chemistry and crystal facet engineering. It was unambiguously demonstrated that a higher solution pH retarded the binding interaction between H+ and oxygen-terminated {001} facets, and also yielded more oxygen vacancies. Therefore, the ab -dominated hierarchical self-assembly was the result. Analysis of photocatalytic properties further manifested that the significant exposure of ab plane is beneficial to photocatalysis. The best pH = 10 catalyst showed the strongest UV absorption, ∼98.5 % of removal efficiency toward the methyl orange molecules within 20 min of simulated solar light irradiation and favorable reusability, while the values are only ∼55.21 % and 50.75 % for the pH = 2 and pH = 12 ones, respectively. This systematic study facilitates a better understanding of photoreaction mechanism of the compound by considering oxygen vacancy defects and electron-hole interaction. [ABSTRACT FROM AUTHOR]

Metastable-state photoacid (mPAH) has become a common tool for controlling and driving chemical processes with light. However, previously developed mPAHs could not be used for reversible protonation of strong bases, including many common amines and heterocycles. In this work, we developed a novel mPAH using benzimidazole as the structural moiety with the active proton. The very low dark acidity of the photoacid avoids the protonation of strong bases in the absence of irradiation. Absorption spectroscopy and NMR studies showed that the photoacid could be paired with NEt3 and DMAP and underwent reversible photoreaction and proton transfer. This new type of photoacid allows the photocontrol of functional materials with strong proton acceptors. [ABSTRACT FROM AUTHOR]

A series of differently substituted β-enaminones 2a,b, 4a–i, 8a–d, and 9–13, their BF2-β-ketoiminate complexes 5a–d, and BF2-β-diketonate complexes 6a–d were prepared as model substrates for photochemical transformations. The attempted photochemical transformations of enaminones 2, 4, 8 and BF2-β-ketoiminate complexes 5 failed. On the other hand, irradiation of mixtures of BF2-β-diketonate complexes 6a–d and cycloalkanes with UV-A light (365 nm) gave the corresponding De Mayo reaction products 7a–f in 9–30% yields. The photochemical ring-expansion of acetyl tetralone-derived BF2-complex 6d gave novel diannulated cyclooctane derivatives 7e and 7f, which would be difficult to obtain using conventional cyclization methods. [ABSTRACT FROM AUTHOR]

Disulfide bonds are ubiquitous molecular motifs that influence the tertiary structure and biological functions of many proteins. Yet, it is well known that the disulfide bond is photolabile when exposed to ultraviolet C (UVC) radiation. The deep-UV-induced S-S bond fragmentation kinetics on very fast timescales are especially pivotal to fully understand the photostability and photodamage repair mechanisms in proteins. In 1,2-dithiane, the smallest saturated cyclic molecule that mimics biologically active species with S-S bonds, we investigate the photochemistry upon 200-nm excitation by femtosecond time-resolved x-ray scattering in the gas phase using an x-ray free electron laser. In the femtosecond time domain, we find a very fast reaction that generates molecular fragments with one and two sulfur atoms. On picosecond and nanosecond timescales, a complex network of reactions unfolds that, ultimately, completes the sulfur dissociation from the parent molecule. [ABSTRACT FROM AUTHOR]

Fatty Acid Esters of Hydroxy Fatty Acids (FAHFAs) have emerged as extraordinary bioactive lipids, exhibiting diverse bioactivities, from the enhancement of insulin secretion and the optimization of blood glucose absorption to anti-inflammatory effects. The intricate nature of FAHFAs' structure reflects a synthetic challenge that requires the strategic introduction of ester bonds along the hydroxy fatty acid chain. Our research seeks to create an effective methodology for generating varied FAHFA derivatives. Our primary approach centers on a photochemical hydroacylation reaction, merging terminal alkenes, either ω-alkenoic acids or ω-alkenyl alcohols, with commercially available aldehydes. This transformative, environmentally friendly process, orchestrated by phenylglyoxylic acid as the photoinitiator, serves as the linchpin in establishing a practical and relatively simple method for constructing a library of racemic FAHFAs. The ketones produced by the photochemical reactions are easily converted to hydroxy derivatives, which are coupled with caproic, palmitic, or oleic acid, providing a large set of FAHFAs, which broaden our ability for future structure–activity relationship studies. [ABSTRACT FROM AUTHOR]

Arsenic (As) is a widespread and highly toxic metalloid that adversely affects plant health, leading to reduced yields, impaired photosynthesis, and compromised root structures. Although acetylcholine (ACh), a neurotransmitter implicated in plant growth and stress responses, has shown potential in mitigating heavy metal stress, its effects on As stress in maize (Zea mays L.) remain largely unexplored. This study investigated the impact of ACh treatments on maize seedlings exposed to As stress (100 µM), focusing on physiological responses, growth rates, photosynthesis, and the antioxidant system. Our findings revealed that ACh treatments conferred differential protective effects against As stress. The lowest concentration (ACh1, 10 µM) enhanced growth by 2.6-fold compared to Asexposed plants, with no significant impact on relative water content (RWC). The medium concentration (ACh2, 50 µM) significantly improved both growth and RWC, effectively mitigating As-induced damage through enhanced osmotic adjustment and reduced oxidative stress. In contrast, the highest concentration (ACh3, 100 µM) yielded mixed results, showing improvements in RWC but minimal effects on growth, potentially due to metabolic imbalances from excessive ACh accumulation. Additionally, ACh2 treatment enhanced photosynthetic efficiency and increased the superoxide dismutase activity by 41% and catalase activity by 10%, facilitating the detoxification of radicals. By promoting the ascorbate-glutathione cycle, ACh supported redox homeostasis, demonstrating its protective role in alleviating As-induced oxidative damage and improving maize resilience under stress conditions. [ABSTRACT FROM AUTHOR]

The emergence of highly wavelength resolved reactivity information for complex photochemical reaction processes allows the establishment of multi‐color reaction modes. One particularly powerful mode is the synergistic two‐color reaction, where two colors of light have to be present in the same volume element to either enable or enhance photochemical reactivity that leads to a specific photoproduct. Herein, we introduce a two‐color synergistic photochemical reaction system based on a diaryl indenone epoxide (DIO) photoswitch and the cis‐to‐trans isomerization of a bridged ring‐strained azobenzene (SA), which respond to ultraviolet (365 nm) and visible light (430 nm), respectively, with different rates, forming a well‐defined heterocyclic photoadduct, DIOSA, that we structurally confirm via single crystal x‐ray diffraction (SXRD). To quantitatively capture the effectiveness of the dual‐color irradiation as a function of the reaction conditions such as light intensity and starting material ratio as a function of product yield, we introduce a parameter, the photochemical synergistic ratio φsyn ${{\phi{} }_{syn}}$. A reduced φsyn ${{\phi{} }_{syn}}$ termed φsyn0 ${{\phi{} }_{syn}^{0}}$ —that extrapolates to conditions of infinitesimal conversions—allows to compare the efficiency of the synergistic photochemistry at varying reaction conditions. [ABSTRACT FROM AUTHOR]

Chalcogen bonding interactions have attracted significant attention in a broad chemistry community, with a particular focus on their ability to stabilise the key transition states in various organic synthetic routes. In this work, we demonstrate that they can also be harnessed in selective photoredox reactions, which cannot be otherwise achieved with alternative approaches to photoreduction. We demonstrate this concept through the photoreduction of the sulfur‐containing DNA nucleoside precursor thioanhydrouridine to 2'‐deoxy‐thiouridine, revealing the previously unrecognized role of bisulfide in this process. Based on quantum chemical simulations, we identify a stable chalcogen‐bonding complex of the hydrosulfide anion and thionhydrouridine (HS−⋅⋅⋅S contacts), which enables directional photoinduced electron transfer, resulting in the formation of non‐canonical DNA nucleoside. We also disprove the possibility that photoreduction of thioanhydronucleosides could be initiated by hydrated electrons generated from irradiated bisulfide anions which do not interact with the chromophore. Finally, we show that selective photoreduction mediated by chalcogen bonds can only occur for chromophores, which exhibit sufficiently long excited‐state lifetimes in the locally‐excited states to undergo transition to the productive charge transfer state. These findings can be further used in the design of similar photoredox reactions which can employ the potential of chalcogen bonding interactions. [ABSTRACT FROM AUTHOR]

Promoting the generation of triplet states is essential for developing efficient photocatalytic systems. This research presents a novel approach of host‐stabilized through‐space conjugation via the combination of covalent and non‐covalent methods. The designed building block, 4,4′‐(1,4(1,4)‐dibenzene cyclohexaphane‐1,4‐diyl)bis(1‐phenylpyridinium) chloride, features inherently stable through‐space conjugation. When this block forms a 1 : 1 host–guest complex with cucurbit[8]uril, the through‐space conjugation is further stabilized within the confined cavity. Both the generation and lifetime of triplet state are significantly increased, resulting from the host‐stabilized through‐space conjugation. Additionally, the ultrahigh binding constant of 6.58×1014 M−1 ensures the persistence of host‐stabilization effect. As a result, the host–guest complex acts as a highly efficient catalyst in the photocatalytic oxidation of thioether and aromatic alcohol. In the photodegradation of lignin, a complex natural product, the host–guest complex also exhibits high efficiency, demonstrating its robustness. This line of research is anticipated to enrich the toolbox of supramolecular photochemistry and provide a strategy for fabricating efficient supramolecular photocatalysts. [ABSTRACT FROM AUTHOR]

Ratiometric optical detection of analytes is a convenient strategy as the technique is devoid of relative error and background correction. Herein, solvent‐guided ratiometric optical recognition of fluoride and bisulfate anions by a low‐cost, "off‐the‐shelf" bioactive molecule, harmane (HRH) is thoroughly explored. Interestingly, solvent plays a dynamic role in the selective recognition of the dual anions via the dual channels of HRH in an intelligent manner. The probe displays high‐fidelity recognition behavior towards fluoride ion in an aprotic solvent (acetonitrile) and towards bisulfate ion in a protic environment (acetonitrile/water; 5:1; v/v). Both the channels of HRH are very selective for a particular anion (F−/HSO4−) in a specific solvent. Organized and comprehensive theoretical calculation denotes that hydrogen bonding between the acidic pyrrolic proton of HRH and fluoride for the first channel and the acidic proton of bisulfate and the pyridinic nitrogen for the second channel of HRH led to the formation of a hydrogen‐bonded ion pair (HBIP). Consequently, significant optical changes are observed in the visible region, which is convenient for real‐life detection of F− and HSO4− independently. The essential role of solvent in tuning the dual channels of HRH is an important artifact in the literature of fundamental photochemistry. [ABSTRACT FROM AUTHOR]

Offering high spatiotemporal resolution, dual wavelength‐controlled soft matter network formation paves the way to advanced printing techniques with optimized performance. One of the most promising approaches is the antagonistic control of covalent bond‐forming reactions with two colors of light, where photoexcitation with one wavelength induces a photochemical reaction, while irradiation with the other ceases it in the presence of the first color. Herein, we combine a photoactivatable diene precursor and a photoswitchable dienophile, establishing a dual‐wavelength‐gated cycloaddition reaction capable of controlling polymer crosslinking. Upon incorporation of the diene precursor into a methacrylate copolymer and the synthesis of a difunctional dienophile cross‐linker, selective polymer network formation is promoted under sole UV illumination, while it can be efficiently suppressed with simultaneous redlight irradiation. Critically, the methodology is used for the preparation of solid polymer materials with antagonistic two‐color control of their cross‐linking status, ultimately allowing the fabrication of spatially patterned polymer films. [ABSTRACT FROM AUTHOR]

The relative impacts of biochemical and stomatal limitations on photosynthesis during photosynthetic induction have been well studied for diverse plants under ambient CO2 concentration (Ca). However, a knowledge gap remains regarding how the various photosynthetic components limit duction efficiency under elevated CO2. In this study, we experimentally investigated the influence of elevated CO2 (from 400 to 800 μmol mol–1) on photosynthetic induction dynamics and its associated limitation components in two broadleaved tree species, Populus tomentosa and Eucalyptus robusta. The results show that elevated CO2 increased the steady-state photosynthesis rate (A) and decreased stomatal conductance (gs) and the maximum carboxylation rate (Vcmax) in both species. While E. robusta exhibited a decrease in the linear electron transport rate (J) and the fraction of open reaction centers in photosynthesis II (qL), P. tomentosa showed a significant increase in non-photochemical quenching (NPQ). With respect to non-steady-state photosynthesis, elevated CO2 significantly reduced the induction time of A following a shift from low to high light intensity in both species. Time-integrated limitation analysis during induction revealed that elevated CO2 reduces the relative impacts of stomatal limitations in both species, consequently shifting the predominant limitation on induction efficiency from stomatal to biochemical components. Additionally, species-specific changes in qL and NPQ suggest that elevated CO2 may increase biochemical limitation by affecting energy allocation between carbon fixation and photoprotection. These findings suggest that, in a future CO2-rich atmosphere, plants productivity under fluctuating light may be primarily constrained by photochemical and non-photochemical quenching. [ABSTRACT FROM AUTHOR]

The photochemical interactions between nitrate (NO3−) and natural organic matter (NOM) are vital for aquatic chemistry. However, the effects of guest iron minerals, which may enter the aquatic environments due to both human and natural activities, on those interactions are widely ignored. This work evaluated the effects of hematite (α-Fe2O3) on the photochemical conversion products and pathways of NO3−, fulvic acid (FA) under 12 h of ultraviolet irradiation. The addition of 0.4 g/L of guest α-Fe2O3 accelerated the reduction of NO3− by 24.3%, with NH4+ as the primary reduction product, and hampered the mineralization of FA. These effects were dependent on the dosage amount of α-Fe2O3 and FA concentrations. The studies on the molecule-level changes of FA revealed that the complete oxidation to CO2 and the partial oxidation pathways that alter the molecular composition of FA were suppressed, and the mineralization rate decreased by 27.8%. Particularly, the conversion rates of CHON and CHONS were reduced by 21.0% and 20.3%, respectively, increasing the unsaturated products. The scavenging experiments and quantitative measurements of hydroxyl radicals (•OH) proposed that the photogenerated electrons and holes from α-Fe2O3 were the key for the altered transformation of NO3− and FA. This work revealed the guest effects of iron mineral particles on the photochemical interactions between NO3− and NOM in the natural surface waters. [ABSTRACT FROM AUTHOR]

Photoactive complexes of nonprecious transition metals, mainly including those in the first-row and partially the second-row of the Periodic table of elements, have received increasing attention in view of their low cost and long-term sustainability. They are recognized as promising alternatives to noble transition metal complex congeners that have been extensively studied in optoelectronic devices, artificial photosynthesis, photocatalysis, biodiagnostics, and therapeutics, etc. This review is devoted to a comprehensive summary on the classical and recent advances on photoactive nonprecious transition metal complexes, including photoactive Zr, V, Cr, Mo, and W complexes, Mn complexes and hybrids, Fe, Co, Ni, and Cu complexes, and Zn and Cd complexes and hybrids. A particular focus is given on the molecular design, modulation of photophysical and photochemical properties, and applications of the representative and lately-developed nonprecious metal complexes. In addition, a perspective on the future development in this field is provided at the end of this review. [ABSTRACT FROM AUTHOR]

Nitroso compounds have emerged as highly valuable reaction partners or reagents in organic synthesis due to their rich reactivity. The versatile profile of these compounds allows them to function as electrophiles, nucleophiles, diradicals, and radical acceptors in diverse transformations. In recent years, notable progress has been made in harnessing photochemical reactions with nitroso compounds to prepare N,O-containing structures using mild and eco-friendly conditions. Various nitroso compounds like nitrosoarenes, acyloxy nitroso compounds, N-nitrosoamines and nitrites have received significant attention for their ability to introduce NO moieties into complex molecules that are otherwise difficult to access. In this review, we provide an overview of the recent advancements in the visible light-induced conversion of nitroso compounds, with particular emphasis on their role as bifunctional reagents and acceptors of radicals, carbenes and nitrenes. [ABSTRACT FROM AUTHOR]

Bisphenol A (BPA, 4,4'-(propane-2,2-diyl)diphenol) is a common plasticizer that is very widespread in the environment and is also found at significant concentrations in the global oceans, due to contamination by plastics. Here we show that triplet sensitization is an important degradation pathway for BPA in natural surface waters, which could prevail if the water dissolved organic carbon is above 2–3 mgC L−1. Bromide levels as per seawater conditions have the potential to slow down BPA photodegradation, a phenomenon that could not be offset by reaction of BPA with Br2•− (second-order reaction rate constant of (2.54 ± 0.09) × 108 M−1 s−1). Ultra-high resolution mass spectrometry revealed that the presence of inorganic salts (NaCl and NaBr) markedly increased the complexity of the observed CHO product compounds formed upon photosensitized degradation of BPA. The obtained results suggest that bisphenols can be efficiently removed by photosensitized reactions and generate higher number of oligomers and polyaromatic compounds in the sea surface and liquid water of marine aerosols compared to freshwaters and/or dilute cloud-water. Considering that polyaromatic compounds absorb solar actinic radiation, these results suggest that inorganic salts could significantly affect the photosensitized degradation of bisphenols and consequently influence the light-absorbing properties of marine aerosols and, ultimately, the Earth's radiative balance. [ABSTRACT FROM AUTHOR]

Chemical modification of carbonaceous materials is a convenient and reliable approach for the permanent fabrication of functional moieties. Among different linkers, diazirines offer a photogenerated reactive carbene that can insert into X–H (X; O, N) and add to π bonds to tether a variety of moieties on the surface of carbonaceous materials. Explicitly, 3‐phenyl‐3‐(trifluoromethyl)‐3H‐diazirine is more thermally and chemically stable within the diazirine family. Here, we synthesized 3‐(ferrocenylalkyloxy)‐3‐(trifluoromethyl)‐diazirine derivatives and utilized them to covalently modify the surface of glassy carbon (GC). The photogenerated carbene enabled the tethering of the ferrocene (Fc) to the surface of a GC electrode (GCE). The modified surface properties were investigated using different electrochemical techniques, ellipsometry spectroscopy, and scanning electron microscopy. Electrochemical surface responses in KCl and Ru(NH3)63+ solutions clearly exhibited ferrocene redox behavior and surface blocking during modification, respectively. Surface analysis results revealed a clear correlation between the thickness and capacitance current of the modified surface. More importantly, the obtained electrochemistry data show substantial chemical stability of the covalently tethered Fc on the GCE surface in both aqueous and nonaqueous media. The presented work offers an approach for the on‐demand photochemical formation of carbene from diazirines to add functionality for applications of modified electrodes in electrocatalysis and sensing. [ABSTRACT FROM AUTHOR]

Over the past 50 years, a principal approach to controlling conventional photochemical reactions has relied on imposing geometric constraints on reactant or transition state via conducting photochemistry in the organized or constraining media. Herein, we describe a fundamentally different approach to affect the course of photochemical reactions (photochemical rearrangements) by utilizing spatially selective excitation of specific electronic transitions with plane‐polarized light in the reactant molecules uniformly aligned in the nematic liquid crystal phase. In particular, we focused on the Type B enone rearrangement of 4,4‐diarylcyclohexenones – one of the most common photochemical rearrangements. We demonstrated that the aryl migratory aptitude in this reaction was attenuated in response to changing an angle between the polarization plane of the incident light and the alignment direction of the nematic liquid crystal, with the enhanced aryl migration achieved when the polarization plane coincided with the transition dipole moment leading to the excited state responsible for this migration. The spatially‐selective initial excitation therefore was overruling the electronic factors responsible for the relative ratio of the two alternative photoproducts. The experimental findings were further supported by the results of a computational study. This work showcases a new fundamental paradigm in controlling photochemical reactivity and selectivity of photoreactions. [ABSTRACT FROM AUTHOR]