Unravelling Supramolecular Photocycloaddition: Cavitand-Mediated Reactivity of 3-(Aryl)Acrylic Acids.

The supramolecular photocycloaddition (PCA) of 3-(phenyl)acrylic acid has been extensively pursued by chemists to study weak interactions and synthesize substituted cyclobutanes. The stereo- and regioselectivity of the products in a supramolecularly affected reaction are often used as a probe for assessing the nature of weak interactions and/or molecular ambience of the reactants. However, some crucial aspects of this chemistry have often remained underexplored in the past, especially within the context of interpreting strength and directionality of interactions based on reaction outcomes. We present a detailed study of the cavitand-mediated PCA of a new and suitable reactant (3-(naphthyl)acrylic acids) that exhibits labile photo-reversible chemistry, which is suitable for exploring previously un-explored aspects of the supramolecular PCA chemistry. Our studies afford important insights about this chemistry that should be considered while using product selectivity as a proxy for deducing intermolecular interactions.

Supramolecular Control of Singlet Oxygen Generation.

Singlet oxygen (1O2) is the excited state electronic isomer and a reactive form of molecular oxygen, which is most efficiently produced through the photosensitized excitation of ambient triplet oxygen. Photochemical singlet oxygen generation (SOG) has received tremendous attention historically, both for its practical application as well as for the fundamental aspects of its reactivity. Applications of singlet oxygen in medicine, wastewater treatment, microbial disinfection, and synthetic chemistry are the direct results of active past research into this reaction. Such advancements were achieved through design factors focused predominantly on the photosensitizer (PS), whose photoactivity is relegated to self-regulated structure and energetics in ground and excited states. However, the relatively new supramolecular approach of dictating molecular structure through non-bonding interactions has allowed photochemists to render otherwise inactive or less effective PSs as efficient 1O2 generators. This concise and first of its kind review aims to compile progress in SOG research achieved through supramolecular photochemistry in an effort to serve as a reference for future research in this direction. The aim of this review is to highlight the value in the supramolecular photochemistry approach to tapping the unexploited technological potential within this historic reaction.

Stereo- and regioselective photocycloaddition of extended alkenes using γ-cyclodextrin.

Photoexcitation of dibenzalacetones (1a-d) in homogeneous media and solid state yields a mixture of products with poor conversions. Irradiation of the reactants complexed to γ-cyclodextrin predominantly affords a single dimer (syn adduct 6) despite the possibility for several monomeric and dimeric products. High selectivity in the cavitand-mediated reaction along with the structural characterization of the inclusion complex provides insight into the supramolecular interactions that drive the self-assembly of the host-guest system.

Antineoplastic Actions of Cinnamic Acids and Their Dimers in Breast Cancer Cells: A Comparative Study.

BACKGROUND/AIM: Breast cancer is the second leading cause of cancer-related deaths in US, which necessitates constant research for medications with minimal adverse effects. The aim of the study was to determine if certain cinnamic acid dimers (CADs) exhibit higher cytotoxicity in breast cancer cells than against non-tumorigenic cells. MATERIALS AND METHODS: These dimers have not been explored, so far, due to their complex stereochemistry; cavitand-mediated photodimerization (CMP) method was used to produce several CADs, which were tested for cytotoxicity, apoptosis and cell cycle inhibition. RESULTS: CADs such as ferulic acid dimer, 3-fluoro CAD, and 3, 4-difluoro CAD, were found to be more cytotoxic than their parent monomers. The most potent compound, 3-fluoro CAD caused apoptosis and 'S' phase cell cycle arrest in cancer cells. CONCLUSION: This study indicates an avenue for research for developing a novel class of antineoplastic compounds that can be synthesized using an easy, economical method.

Capturing circulating tumor cells of hepatocellular carcinoma.

Early metastases of hepatocellular carcinoma (HCC) may be detected by the isolation of circulating tumor cells (CTCs) in the bloodstream. During the course of therapeutic attempts, monitoring CTC changes in patients with HCC is helpful for the efficacy assessment. Nevertheless, the markers used for the detection, such as α-feto protein, asialoglycoprotein receptor or epithelial cell adhesion molecule, CD133 or CD90, are not specific for HCC CTCs. In spite of these limitations, a timely determination of the existence of CTCs will be beneficial for the monitoring of distant metastases, the evaluation of therapeutic attempts, and the prediction of prognosis.