Chemists have long pursued harnessing light energy and photoexcitation processes for synthetic transformations. Ligand-to-metal charge transfer (LMCT) in high-valent metal complexes often triggers bond homolysis, generating oxidized ligand-centered radicals and reduced metal centers. While photoinduced oxidative activations can be enabled, this process, typically seen as photochemical decomposition, remains underexplored in catalytic applications. To mitigate decomposition during LMCT excitation, we developed a catalytic cycle integrating in situ coordination, LMCT, and ligand homolysis to activate ligated alcohols transiently into alkoxy radicals. This catalytic approach leverages Ce(IV) LMCT excitation and highly reactive alkoxy radical intermediates for selective functionalizations of C(sp(3))-H and C(sp(3))-C(sp(3)) bonds under mild conditions. In this Account, we discuss these advancements, highlighting the practical utility of cost-effective cerium salts as catalysts and their potential to develop innovative transformations, addressing long-standing synthetic challenges. Selective functionalization of chemically inert C(sp(3))-H bonds has long posed a significant challenge. We first detail our research using LMCT-enabled alkoxy radical-mediated hydrogen atom transfer (HAT) processes for selective C(sp(3))-H functionalizations. Using readily available CeCl3, we established a general protocol for employing free alcohols in the Barton reaction. By integrating LMCT and HAT catalysis, we introduced a selective photocatalytic strategy for functionalizing feedstock alkanes, converting gaseous hydrocarbons into valuable products. Employing simple cerium salts like Ce(OTf)(3) and CeCl3, we achieved selective C-H amination of methane and ethane at ambient temperature, achieving turnover numbers of 2900 and 9700, respectively. This catalytic manifold has been further exploited to address the site-selectivity challenge in the C-H functionalization of linear alkanes. The use of methanol as a cocatalyst enabled preferential functionalization of the most electron-rich sites, achieving a high intrinsic selectivity over 12:1 of secondary vs primary sites in pentane and hexane. Next, we discuss the catalytic utilization of alkoxy-radical-mediated beta-scission, a frequently encountered side reaction in HAT transformations, for selective cleavage and functionalization of C-C bonds. The versatility of the LMCT catalytic platform facilitates the generation of alkoxy radicals from various free alcohols. In our initial demonstration of LMCT-enabled C(sp(3))-C(sp(3)) bond activation, we developed a cerium-catalyzed ring-opening and amination of cycloalkanols, providing an effective protocol for cleaving unstrained C-C bonds. This strategy has been successfully applied to various radical cross-coupling processes, leading to innovative transformations such as ring expansions of cycloalkanols, dehydroxymethylative alkylation, amination, alkenylation, and ring expansions of cyclic ketones. These results highlight the synthetic potential of employing LMCT-mediated beta-scission and ubiquitous C-C bonds as unconventional functional handles for generating molecular complexity. Lastly, we delve into our mechanistic investigations. Beyond the catalytic application of Ce(IV) LMCT in various transformations, we have undertaken comprehensive mechanistic studies. These investigations encompass characterization of Ce(IV) alkoxide complexes to elucidate their structures, evaluation of their photoactivity and selectivity in radical generation, and elucidation of kinetic pathways associated with transient LMCT excited states. Our research has revealed ultrafast bond homolysis, back electron transfer, and the selectivity of heteroleptic complexes in homolysis, providing crucial insights for advancing LMCT catalysis.

Trinitromethyl and N-amino groups were innovatively incorporated into the framework of 1,2,4-triazole, resulting in 1-amino-5-nitro-3-(trinitromethyl)-1,2,4-triazole (2). Ammonium and hydrazinium salts of 1-amino-5-nitro-3-(dinitromethyl)-1,2,4-triazole were synthesized by acidification, extraction, and neutralization with bases from the potassium salt. All of the newly prepared energetic compounds were comprehensively characterized by using infrared spectroscopy, elemental analysis, nuclear magnetic resonance spectroscopy, and single crystal X-ray diffraction. Compound 2 exhibits favorable properties such as positive oxygen balance (OBCO2 = 5.8%), high density (1.88 g cm(-1)), good detonation performances (v(D) = 8937 m s(-1), P = 35.5 GPa), and appropriate friction sensitivity (FS = 144 N). The potassium salt 3 demonstrates good thermal decomposition temperature (181 degrees C) and high density (1.98 g cm(-1)), while the ammonium salt and hydrazinium salt also display good thermal decomposition temperatures of 183 and 176 degrees C, respectively. Among these compounds, the ammonium salt exhibits the lowest mechanical sensitivities (FS = 144 N, IS = 6 J).

We report a systematic molecular design in BF(2)bdk-based afterglow emitters with photoluminescence quantum yields up to 46.3% and lifetimes around 1 s. Suitable excited-state types, diverse excited state species, relatively small singlet-triplet energy gaps and strong dipole-dipole interactions are critical in determining the afterglow properties.

Molecular diffusion and surface dynamics within two covalent organic frameworks (COFs) have been investigated using nuclear magnetic resonance (NMR) pulsed-field gradient (PFG) and relaxation. The effect of chemical functionalities of the COFs on the effective self-diffusivity of the probe molecules within the pore space and the adsorbate/adsorbent interactions were investigated. In particular, diffusion and interaction of water, methanol, n-octane, and 1,3,5-triisopropylbenzene (1,3,5-TIPB) within COF-SIOC and COF-DHTA were assessed. The two types of COFs used in this study possessed a dual pore Kagome structure consisting of larger hexagonal and smaller triangular pores. The PFG NMR results show the presence of two distinct diffusion coefficients for small probe molecules, such as water, methanol, and n-octane. This behaviour is attributed to their relatively smaller kinetic diameters, allowing them to access both smaller and larger pores in the COFs. In contrast, the PFG diffusion plot for 1,3,5-TIPB showed a single component linear behaviour, which is attributed to diffusion through the larger hexagonal pores only, as a result of a much larger kinetic diameter of 1,3,5-TIPB compared to the other probe molecules, which prevents access to the smaller triangular pores. The presence of functional groups affects surface interactions between the probe molecules and the surface of the COFs. The NMR T-1/T-2 relaxation measurements reveal a higher strength of surface interaction for water molecules in COF-DHTA compared to COF-SIOC, which is attributed to the presence of hydrophilic -OH groups in COF-DHTA. Conversely, a higher strength of surface interactions was achieved for n-octane in COF-SIOC, due to the hydrophobic nature of this material. This work reports new insights into transport and dynamics of molecules confined in COFs, which can help design and optimisation of such pore structures in applications such as separation and catalysis.