Direct formation of fullerene monolayers using [4+2] Diels-Alder cycloaddition.

International audienceThe formation of covalent C(60) monolayers through [4+2] Diels-Alder cycloaddition between C(60) and anthracene monolayers grafted onto a silicon oxide surface was investigated by ellipsometry, fluorescence and by atomic force microscopy

Regulating Signal Enhancement with Coordination-Coupled Deprotonation of a Hydrazone Switch

Proton relay plays an important role in many biocatalytic pathways. In order to mimic such processes in the context of molecular switches, we developed coordination-coupled deprotonation (CCD) driven signaling and signal enhancement sequences. This was accomplished by using the zinc(ii)-initiated CCD of a hydrazone switch to instigate an acid catalyzed imine bond hydrolysis that separates a quencher from a fluorophore thus leading to emission amplification. Because CCD is a reversible process, we were able to show that the catalysis can be regulated and turned “on” and “off” using a metalation/demetalation cycle

Sperm Motility Regulatory Proteins: A Tool to Enhance Sperm Quality

Sperm forward motility is an essential parameter in mammalian fertilization. Studies from our laboratory have identified and characterized a few unique sperm motility regulatory proteins/glycoproteins from the male reproductive fluids and mammalian blood serum. The purified sperm motility-initiating protein (MIP) from caprine epididymal plasma as well as the forward motility-stimulating factor (FMSF) and motility-stimulating protein (MSP) from buffalo and goat serum, respectively, have high efficacy to initiate or increase motility in nonmotile or less motile sperm. Antibody of sperm motility inhibitory factor (MIF-II) has the high potential to enhance sperm vertical velocity and forward motility by increasing intracellular cyclic adenosine monophosphate (cAMP) level. The appearance and disappearance of D-galactose–specific lectin and its receptor along the epididymis has been reported to be involved in motility regulation in spermatozoa. A novel synthetic cryopreservation method and role of lipid to protect membrane damage during cryopreservation have been demonstrated. Motility-promoting proteins may be extremely useful for improving cattle breeding and breeding of endangered species, thereby helping in enhanced production of animal products as well as in the conservation of animals. Isolated proteins and developed cryopreservation technology may also be beneficial in human infertility clinics to increase the chance of fertilization

Asymmetric-donor (D₂D₂′)–acceptor (A) conjugates for simultaneously accessing intrinsic blue-RTP and blue-TADF

Asymmetric-donor–acceptor (D2D2′–A) conjugates for simultaneously accessing blue room-temperature phosphorescence (BRTP) and blue thermally activated delayed fluorescence (BTADF).</p

Use of Dimeric Excited States of the Donors in D₄‑A Systems for Accessing White Light Emission, Afterglow, and Invisible Security Ink

Pure organic white light emitters with an afterglow (AG) feature have unique advantages and various potential applications. However, the studies of single-component organic white light emitters with AG and visible light excitation (VLE)-dependent efficient room-temperature phosphorescence (RTP) features remain a challenging area of research in photophysics. Herein, we synthesize three terephthalonitriles in which 2,3,5,6-positions are covalently attached to 2-fluoro-phenoxy (TOF), 2-chloro-phenoxy (TOC), and 2-methoxy-phenoxy groups (TOM) to give twisted geometries. We observed that powder samples of both TOC and TOM show white light emission with CIE coordinates of (0.32, 0.38) and (0.26, 0.33), respectively, while TOM gives VLE-dependent efficient RTP under ambient conditions. In addition, both TOC and TOF exhibit a dim AG feature. Spectroscopic studies reveal that dual emission of these chromophores originates via radiative decay of monomeric excited states (singlet, triplet), dimer-like excited states (DLES) (singlet, triplet), and aggregated triplet states. Detailed spectroscopic and X-ray analyses reveal the signature of DLES that is formed via conformational reorganization of the phenoxy donors in the excited states. Single-crystal X-ray diffraction analysis shows that the multiple lp­(O)···π­(CN)/CC, Cl/F···π, and hydrogen-bonding interactions in the X-ray structures play a significant role in facilitating intersystem crossing, stabilizing multiple triplet states, and suppressing nonradiative decay, thereby triggering dim afterglow under ambient conditions. We found that TOC and TOF exhibit persistent RTP (PRTP) with lifetimes of 139 and 736 ms, respectively, when they are embedded in the polyvinyl alcohol matrix. Given the PRTP feature, invisible security ink application is developed. These results provide a guidance to design white light-emitting materials with afterglow and visible light-activated efficient RTP features

Use of Dimeric Excited States of the Donors in D₄‑A Systems for Accessing White Light Emission, Afterglow, and Invisible Security Ink

Pure organic white light emitters with an afterglow (AG) feature have unique advantages and various potential applications. However, the studies of single-component organic white light emitters with AG and visible light excitation (VLE)-dependent efficient room-temperature phosphorescence (RTP) features remain a challenging area of research in photophysics. Herein, we synthesize three terephthalonitriles in which 2,3,5,6-positions are covalently attached to 2-fluoro-phenoxy (TOF), 2-chloro-phenoxy (TOC), and 2-methoxy-phenoxy groups (TOM) to give twisted geometries. We observed that powder samples of both TOC and TOM show white light emission with CIE coordinates of (0.32, 0.38) and (0.26, 0.33), respectively, while TOM gives VLE-dependent efficient RTP under ambient conditions. In addition, both TOC and TOF exhibit a dim AG feature. Spectroscopic studies reveal that dual emission of these chromophores originates via radiative decay of monomeric excited states (singlet, triplet), dimer-like excited states (DLES) (singlet, triplet), and aggregated triplet states. Detailed spectroscopic and X-ray analyses reveal the signature of DLES that is formed via conformational reorganization of the phenoxy donors in the excited states. Single-crystal X-ray diffraction analysis shows that the multiple lp­(O)···π­(CN)/CC, Cl/F···π, and hydrogen-bonding interactions in the X-ray structures play a significant role in facilitating intersystem crossing, stabilizing multiple triplet states, and suppressing nonradiative decay, thereby triggering dim afterglow under ambient conditions. We found that TOC and TOF exhibit persistent RTP (PRTP) with lifetimes of 139 and 736 ms, respectively, when they are embedded in the polyvinyl alcohol matrix. Given the PRTP feature, invisible security ink application is developed. These results provide a guidance to design white light-emitting materials with afterglow and visible light-activated efficient RTP features