Binderupringgaard8791

It is suggested that the drastic elongation of fluorescence lifetimes is due to the change in the electronic structure of the first excited state from nπ* to ππ*, resulting in the decreasing spin-orbit coupling to T1 (ππ*).The conformation and electronic structure of dibenzo-24-crown-8 (DB24C8) complexes with K+ ion were examined by ion mobility-mass spectrometry (IM-MS), ultraviolet (UV) photodissociation (UVPD) spectroscopy in the gas phase, and fluorescence spectroscopy in solution. Three structural isomers of DB24C8 (SymDB24C8, Asym1DB24C8, and Asym2DB24C8) in which the relative positions of the two benzene rings were different from each other were investigated. The IM-MS results at 86 K revealed a clear separation of two sets of conformers for the K+(SymDB24C8) and K+(Asym1DB24C8) complexes whereas the K+(Asym2DB24C8) complex revealed only one set. The two sets of conformers were attributed to the open and closed forms in which the benzene-benzene distances in the complexes were long (>6 Å) and short ( less then 6 Å), respectively. IM-MS at 300 K could not separate the two conformer sets of the K+(SymDB24C8) complex because the interconversion between the open and closed conformations occurred at 300 K and not at 86 K. Theion of appropriate bulky groups, such as aromatic rings to host molecules, could reveal the dynamic aspects of encapsulation in host-guest systems.Fluorescence imaging at longer wavelengths, especially in the shortwave-infrared (SWIR 1000-1700 nm) region, leads to a substantial decrease in light attenuation, scattering, and background autofluorescence, thereby enabling enhanced penetration into biological tissues. The limited selection of fluorescent probes is a major bottleneck in SWIR fluorescence imaging. Here, we develop SWIR-emitting nanoparticles composed of donor-acceptor-type conjugated polymers. The bright SWIR fluorescence of the polymer dots (primarily attributable to their large absorption cross-section and high fluorescence saturation intensity (as high as 113 kW·cm-2)) enables the unprecedented detection of single particles as small as 14 nm through millimeter-thick turbid media. Unlike most SWIR-emitting nanomaterials, which have an excited-state lifetime in the range of microseconds to milliseconds, our polymer dots exhibit a subnanosecond excited-state lifetime. These characteristics enable us to demonstrate new time-gated single-particle imaging with a high signal-to-background ratio. These findings expand the range of potential applications of single-particle deep-tissue imaging.As an emerging ultrathin semiconductor material, Bi2O2Se exhibits prominent performances in electronics, optoelectronics, ultrafast optics, etc. However, until now, the in-plane growth of Bi2O2Se thin films is mostly fulfilled on atomically flat mica substrates with interfacial electrostatic forces setting obstacles for Bi2O2Se transfer to fabricate functional van der Waals heterostructures. In this work, controlled growth of inclined Bi2O2Se ultrathin films is realized with apparently reduced interfacial contact areas upon mica flakes. Consequently, the transfer of Bi2O2Se could be facile by overcoming weaker electrostatic interactions. From cross-sectional characterizations at the Bi2O2Se/mica interfaces, it is found that there are no oxide buffer layers in existence for both in-plane and inclined growths, while the un-neutralized charge density is apparently decreased for inclined films. Liraglutide supplier By mechanical pressing, inclined Bi2O2Se could be transferred onto SiO2/Si substrates, and back-gated Bi2O2Se field effect transistors are fabricated, outperforming previously reported in-plane Bi2O2Se devices transferred with the assistance of corrosive acids and adhesive polymers. Furthermore, Bi2O2Se/graphene heterostructures are fulfilled by a probe tip to fabricate hybrid phototransistors with pristine interfaces, exhibiting highly efficient photoresponses. The results in this work demonstrate the potential of inclined Bi2O2Se to act as a building block for prospective van der Waals heterostructures.Nanotheranostics based on tumor-selective small molecular prodrugs could be more advantageous in clinical translation for cancer treatment, given its defined chemical structure, high drug loading efficiency, controlled drug release, and reduced side effects. To this end, we have designed and synthesized a reactive oxygen species (ROS)-activatable heterodimeric prodrug, namely, HRC, and nanoformulated it for tumor-selective imaging and synergistic chemo- and photodynamic therapy. The prodrug consists of the chemodrug camptothecin (CPT), the photosensitizer 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH), and a thioketal linker. Compared to CPT- or HPPH-loaded polymeric nanoparticles (NPs), HRC-loaded NPs possess higher drug loading capacity, better colloidal stability, and less premature drug leakage. Interestingly, HRC NPs were almost nonfluorescent due to the strong π-π stacking and could be effectively activated by endogenous ROS once entering cells. Thanks to the higher ROS levels in cancer cells than normal cells, HRC NPs could selectively light up the cancer cells and exhibit much more potent cytotoxicity to cancer cells. Moreover, HRC NPs demonstrated highly effective tumor accumulation and synergistic tumor inhibition with reduced side effects on mice.Developing a methodology to build target structures is one of the major themes of synthetic chemistry. However, it has proven to be immensely challenging to achieve multilevel elaborate molecular architectures in a predictable way. Herein, we describe the self-assembly of a series of pinwheel-shaped starlike supramolecules through three rationally preorganized metalloligands L1-L3. The key octa-uncomplexed terpyridine (tpy) metalloligand L3, synthesized with an 8-fold Suzuki coupling reaction to metal-containing complexes, has four different types of terpyridines connected with three ⟨tpy-Ru2+-tpy⟩ units, making this the most subunits known so far for a preorganized module. Based on the principle of geometric complementation and the high "density of coordination sites", these metalloligands were assembled with Zn2+ ions to form a pinwheel-shaped star trigon P1, pentagram P2, and hexagram P3 with precisely controlled shapes in nearly quantitative yields. With molecular weights ranging from 16756 to 56053 Da and diameters of 6.