DNA-encoded library technology (DELT) was introduced to our medicinal chemistry society more than 20 years ago. The application of DELT in the development of clinical candidates has been actively reported in the literature recently. A few representative examples include RIP1K inhibitors for inflammatory diseases and sEH inhibitors for endothelial dysfunction or abnormal tissue repair, among many others. Here, the authors would like to recall the recent developments in on-DNA synthetic methodologies for DEL construction and to analyze recent examples in the literature of DELT-based drug development efforts pursued in both the academic and industrial sectors. With this perspective, we hope to provide a useful summary of recent DELT-based drug discovery research and to discuss the future scope of DELT in medicinal chemistry.We report on the temperature- and structural-dependent optical properties and photophysics of a set of boron dipyrromethene (BODIPY) dyes with different substitution patterns of their meso-aryl subunit. Single-crystal X-ray diffraction analysis of the compounds enabled a classification of the dyes into a sterically hindered and a unhindered group. The steric hindrance refers to a blocked rotational motion of the aryl subunit around the bond connecting this moiety to the meso-position of the BODIPY core. The energy barriers related to this rotation were simulated by DFT calculations. As follows from the relatively low rotational barrier calculated to about 17 kcal/mol, a free rotation is only possible for sterically unhindered compounds. Rotational barriers of more than 40 kcal/mol determined for the sterically hindered compounds suggest an effective freezing of the rotational motion in these molecules. With the aid of temperature-dependent spectroscopic measurements, we could show that the ability to rotate directly affects the optical properties of our set of BODIPY dyes.  https://www.selleckchem.com/products/ziritaxestat.html  This accounts for the strong temperature dependence of the fluorescence of the sterically unhindered compounds which show a drastic decrease in fluorescence quantum yield and a significant shortening in fluorescence lifetime upon heating. The optical properties of the sterically hindered compounds, however, are barely affected by temperature. Our results suggest a nonradiative deactivation of the first excited singlet state of the sterically unhindered compounds caused by a conical intersection of the potential energy surfaces of the ground and first excited state which is accessible by rotation of the meso-subunit. This is in good agreement with previously reported deactivation mechanisms. In addition, our results suggest the presence of a second nonradiative depopulation pathway of the first excited singlet state which is particularly relevant for the sterically hindered compounds.Two low-energy excitations of a single water molecule are observed via inelastic electron tunneling spectroscopy, where a significant enhancement is achieved by attaching the molecule to the tip apex in a scanning tunneling microscope. Density functional theory simulations and quantum mechanical calculations of an asymmetric top are carried out to reveal the origin of both excitations. Variations in tunneling junction separation give rise to the quantum confinement effect on the quantum state of a water molecule in the tunneling junction. Our results demonstrate a potential method for measuring the dynamic behavior of a single molecule confined in a tunneling junction, where the molecule-substrate interaction can be purposely tuned.Diisopropylammonium salts have drawn attention in recent years due to their room-temperature ferroelectric properties. Triclinic diisopropylammonium perchlorate (DIPAP) exhibits ferroelectricity at room temperature. We have carried out density functional theory calculations to assign the phonon modes in DIPAP. High-pressure Raman spectra of DIPAP are recorded up to ∼3 GPa. Discontinuity in the NH2 bending and stretching mode frequencies and the appearance of new bands at 0.7 GPa suggest a phase transition by a rearrangement in the hydrogen network. Broadening of lattice modes at 1.3-1.7 GPa indicates a loss of crystalline nature above 1.7 GPa. High-pressure synchrotron X-ray diffraction of DIPAP shows an isostructural phase transition at 0.6 GPa and confirms amorphization at 1.5 GPa that may lead to a loss of ferroelectricity above this pressure. The ambient phase becomes reversible after releasing the pressure. The bulk modulus of DIPAP is determined to be 16.5 GPa.The covalent chemical bond is intimately linked to electron sharing between atoms. The recent independent gradient model (IGM) and its δg descriptor provide a way to quantify locally this electron density interpenetration from wavefunction calculations. Each bond has its own IGM-δgpair signature. The present work establishes for the first time a strong link between this bond signature and the physically grounded bond force constant concept. Analyzing a large set of compounds and bonds, the intrinsic bond strength index (IBSI) emerges from the IGM formulation. Our study shows that the IBSI does not belong to the class of conventional bond orders (like Mulliken, Wiberg, Mayer, delocalization index, or electron localization function-ELF), but is rather a new complementary index, related to the bond strength. A fundamental outcome of this research is a novel index allowing to range all two-center chemical bonds by their intrinsic strength in molecular situation. We believe that the IBSI is a powerful and robust tool for interpretation accessible to a wide community of chemists (organic, inorganic chemistry, including transition-metal complexes and reaction mechanisms).Photodynamic therapy (PDT) has emerged as a promising noninvasive treatment option for cancers and other diseases. The key factor that determines the effectiveness of PDT is the photosensitizers (PSs). Upon light irradiation, the PSs would be activated, produce reactive oxygen species (ROS), and induce cell death. One of the challenges is that traditional PSs adopt a large flat disc-like structure, which tend to interact with the adjacent molecules through strong π-π stacking that reduces their ROS generation ability. Aggregation-induced emission (AIE) molecules with a twisted configuration to suppress strong intermolecular interactions represent a new class of PSs for image-guided PDT. In this Miniperspective, we summarize the recent progress on the design rationale of AIE-PSs and the strategies to achieve desirable theranostic applications in cancers. Subsequently, approaches of combining AIE-PS with other imaging and treatment modalities, challenges, and future directions are addressed.