Organic solid-state fluorescent crystals have received extensive attention owing to their remarkable and promising optoelectronic applications in many fields. Current methods to obtain organic fluorescent crystals usually involve two steps (1) solution phase organic synthesis and (2) crystallization of target fluorescent compounds. Direct transformation from nonfluorescent organic crystals to fluorescent organic crystals by postsynthetic modification (PSM) might be a potential alternative to the traditional methods. Although it is common to implement PSM for porous frameworks, it remains a huge challenge for nonporous organic crystals. Herein, we report a novel method of multistep solid-vapor PSM in nonporous adaptive crystals (NACs) of a pillar[4]arene[1]quinone (M1) to prepare organic solid-state fluorescent crystals. Fluorescent organic crystals can be simply generated when guest-free M1 crystals were exposed to ethylenediamine (EDA) vapor. However, only nonemissive crystals of a thermodynamically metastable intermediate M2 are obtained through solid-vapor single-crystal-to-single-crystal transformation of CH3CN-loaded M1 crystals. Solution-phase reaction of M1 with EDA affords three distinct compounds with different fluorescent properties, which are demonstrated to be the main components of the fluorescent organic crystals that are generated by the solid-vapor PSM. Mechanistic studies show that the pillararene skeleton not only induces the solid-vapor PSM by physical adsorption of EDA but also facilitates the fluorescent emission in the solid state by restricting intermolecular π-π interactions to avoid aggregation-caused quenching (ACQ). Furthermore, this interesting phenomenon is applied for facile fluorescence turn-on sensing of EDA vapor to distinguish EDA from other aliphatic amines.A low-coordinate, high spin (S = 3/2) organometallic iron(I) complex is a catalyst for the isomerization of alkenes. A combination of experimental and computational mechanistic studies supports a mechanism in which alkene isomerization occurs by the allyl mechanism.  https://www.selleckchem.com/products/Acadesine.html  Importantly, while substrate binding occurs on the S = 3/2 surface, oxidative addition to an η1-allyl intermediate only occurs on the S = 1/2 surface. Since this spin state change is only possible when the alkene substrate is bound, the catalyst has high immunity to typical σ-base poisons due to the antibonding interactions of the high spin state.Transformations between different atomic configurations of a material oftentimes bring about dramatic changes in functional properties as a result of the simultaneous alteration of both atomistic and electronic structure. Transformation barriers between polytypes can be tuned through compositional modification, generally in an immutable manner. Continuous, stimulus-driven modulation of phase stabilities remains a significant challenge. Utilizing the metal-insulator transition of VO2, we exemplify that mobile dopants weakly coupled to the crystal lattice provide a means of imbuing a reversible and dynamical modulation of the phase transformation. Remarkably, we observe a time- and temperature-dependent evolution of the relative phase stabilities of the M1 and R phases of VO2 in an "hourglass" fashion through the relaxation of interstitial boron species, corresponding to a 50 °C modulation of the transition temperature achieved within the same compound. The material functions as both a chronometer and a thermometer and is "reset" by the phase transition. Materials possessing memory of thermal history hold promise for applications such as neuromorphic computing, atomic clocks, thermometry, and sensing.Photocages are light-sensitive chemical protecting groups that give investigators control over activation of biomolecules using targeted light irradiation. A compelling application of far-red/near-IR absorbing photocages is their potential for deep tissue activation of biomolecules and phototherapeutics. Toward this goal, we recently reported BODIPY photocages that absorb near-IR light. However, these photocages have reduced photorelease efficiencies compared to shorter-wavelength absorbing photocages, which has hindered their application. Because photochemistry is a zero-sum competition of rates, improvement of the quantum yield of a photoreaction can be achieved either by making the desired photoreaction more efficient or by hobbling competitive decay channels. This latter strategy of inhibiting unproductive decay channels was pursued to improve the release efficiency of long-wavelength absorbing BODIPY photocages by synthesizing structures that block access to unproductive singlet internal conversion conicd in HeLa cells using red light.The bias and temperature dependence of both dark and photoinduced currents in carbon-based molecular junctions were examined over a wide range of oligomeric layer thickness (d) values from 4 to 60 nm. The dark current density versus bias (JV) response of nitroazobenzene molecular junctions exhibits the exponential thickness dependence consistent with coherent tunneling when d 50 nm and avoid the usually strong temperature dependence observed in thicker organic films.The dimeric diketopiperazine (DKPs) alkaloids are a diverse family of natural products (NPs) whose unique structural architectures and biological activities have inspired the development of new synthetic methodologies to access these molecules. However, catalyst-controlled methods that enable the selective formation of constitutional and stereoisomeric dimers from a single monomer are lacking. To resolve this long-standing synthetic challenge, we sought to characterize the biosynthetic enzymes that assemble these NPs for application in biocatalytic syntheses. Genome mining enabled identification of the cytochrome P450, NzeB (Streptomyces sp. NRRL F-5053), which catalyzes both intermolecular carbon-carbon (C-C) and carbon-nitrogen (C-N) bond formation. To identify the molecular basis for the flexible site-selectivity, stereoselectivity, and chemoselectivity of NzeB, we obtained high-resolution crystal structures (1.5 Å) of the protein in complex with native and non-native substrates. This, to our knowledge, represents the first crystal structure of an oxidase catalyzing direct, intermolecular C-H amination.