The design of molecular solar fuels is challenging because of the long list of requirements these molecules have to fulfil: storage density, solar harvesting capacity, robustness, and heat release ability. All of these features cause a paradoxical design due to the conflicting effects found when trying to improve any of these properties. In this contribution, we will review different types of compounds previously suggested for this application. Each of them present several advantages and disadvantages, and the scientific community is still struggling to find the ideal candidate suitable for practical applications. The most promising results have been found using norbornadiene-based systems, although the use of other alternatives like azobenzene or dihydroazulene cannot be discarded. In this review, we primarily focus on highlighting the optical and photochemical aspects of these three families, discussing the recently proposed systems and recent advances in the field.

Metal-free, photoinduced asymmetric deuterosilylation of exocyclic olefins has been achieved using a mannose-derived thiol catalyst.

Generation of carbon centered radicals from organic halides represents a powerful tool in modern organic chemistry, especially in the context of photoredox catalysis. However, activation of carbon–halogen bonds is usually promoted by toxic and hazardous tin reagents. Alternatively, α‐aminoalkyl radicals have emerged as a cheap and efficient halogen atom transfer (XAT) reagents, although the activation mechanism is still underexplored with respect to hydrogen atom transfer (HAT) chemistry. Herein, we report a computational systematic evaluation of four different α‐aminoalkyl radicals on the Halogen Atom Transfer (XAT) mechanism. We have evaluated up to 32 reactions, including two different types of substrates (Ph−X and Cy−X). This systematic study aims to provide a big picture on the key effects in this reactivity including the hybridization of carbon, the nature of the halogen, and the electronics/sterics of the α‐aminoalkyl radical.

Sunscreens provide a frontline defense for our DNA against the damage caused by ultraviolet (UV) radiation. The active ingredients in topically applied sunscreens that provide this defense are UV filters, which preferentially absorb or reflect UV radiation before it penetrates the skin and interacts with photosensitive nucleic acids. However, there are concerns related to human and environmental toxicity of current UV filters, and consequently a shift toward nature‐inspired, particularly microbial, UV filters. In this paper, new physical insight is provided into the fundamental mechanisms of photoprotection in two synthetic analogs of mycosporine‐like amino acid‐type UV filters, demonstrating new methods of protection that are distinct from those of current commercial sunscreens, extending previous work in this area. Transient absorption measurements (both transient electronic absorption spectroscopy and transient vibrational absorption spectroscopy) are combined with steady‐state studies and high‐level computational results to aid our mapping of the experimentally derived lifetimes to real‐time photodynamic processes. The conclusions reached here pave the way toward developing new and more efficient biomimetic DNA photoprotectant materials.

Avobenzone is one of the most widely used sunscreens in skin care formulations, but suffers from some drawbacks, including photo instability. To mitigate this critical issue, the use of octocrylene as a stabilizer is a common approach in these products. However, octocrylene has been recently demonstrated to show potential phototoxicity. The aim of this work is to analyze the performance of a series of mycosporine-like amino acid (MAA)-inspired compounds to act as avobenzone stabilizers as an alternative to octocrylene. Different avobenzone/MAA analogue combinations included in galenic formulations were followed under increasing doses of solar-simulated UV radiation. Some of the synthetic MAA analogues analyzed were able to increase by up to two times the UV dose required for 50% of avobenzone photobleaching. We propose some of these MAA analogues as new candidates to act as avobenzone-stabilizing compounds in addition to their UV absorbance and antioxidant properties, together with a facile synthesis.

Up-Conversion materials have received great attention in drug delivery applications in recent years. A specifically emerging field includes the development of strategies focusing on photon processes that promote the development of novel platforms for the efficient transport and the controlled release of drug molecules in the harsh microenvironment. Here, modified reaction time, thermal treatment, and pH conditions were controlled in the synthesis of NaYF₄:Yb,Tm up-converted (UC) material to improve its photoluminescence properties. The best blue-emission performance was achieved for the UC3 sample prepared through 24 h-synthesis without thermal treatment at a pH of 5, which promotes the presence of the β-phase and smaller particle size. NaYF₄:Yb,Tm has resulted in a highly efficient blue emitter material for light-driven drug release under near-IR wavelength. Thus, NaYF₄:Yb,Tm up-converted material promotes the N-O bond cleavage of the oxime ester of Ciprofloxacin (prodrug) as a highly efficient photosensitized drug delivery process. HPLC chromatography and transient absorption spectroscopy measurements were performed to evaluate the drug release conversion rate. UC3 has resulted in a very stable and easily recovered material that can be used in several reaction cycles. This straightforward methodology can be extended to other drugs containing photoactive chromophores and is present as an alternative for drug release systems.