This paper presents synthesis and photophysical investigation of cyclometalated water-soluble Pt(II) and Ir(III) complexes containing auxiliary sulfonated diphosphine (bis(diphenylphosphino)benzene (dppb), P^P*) ligand. The complexes demonstrate considerable variations in excitation (extending up to 450 nm) and emission bands (with maxima ranging from ca. 450 to ca. 650 nm), as well as in the sensitivity of excited state lifetimes to molecular oxygen (from almost negligible to more than 4-fold increase in degassed solution). Moreover, all the complexes possess high two-photon absorption cross sections

Phenothiazine derivatives based on the 10-phenyl-10H-phenothiazine (NAS)c hromophore,n amely 7-phenyl-7H-benzo[c]phenothiazine (NAS-1)a nd 12-phenyl-12Hbenzo[a]phenothiazine (NAS-2), were designed and synthesized. NAS-1 and NAS-2 are constitutional isomers with different steric strains imposed on the phenothiazine core moiety.Insolution, the more-strained NAS-2 possesses abent structure and undergoes photoinduced structural planarization (PISP). In the crystal, despite the absence of PISP,bent NAS-2 exhibits prominent excimer emission as well as emission mechanochromism, which is not observed in the planar-like NAS and NAS-1.T his unconventional observation results from the bent core structure facilitating p-p stacking of the peripheral naphthalene moieties.T wo-photon-coupled depthdependent emission shows spectral differences between the surface and kernel of the NAS-2 crystal, and is believed to be ageneral phenomenon, at least in part, for materials exhibiting emission mechanochromism. Photoinducedstructuralplanarization(PISP)isafascinatingand promising phenomenon that has received much attention. [1] Recent examples are focused on the class of molecules bearing an N,N'-disubstituted-dihydrodibenzo[a,c]phenazine chromophore (DPAC ;s ee Figure 1a). [2] Different from the early reported PISP molecules that reveal an intrinsic nonplanar structure free from steric perturbation, [2] bent DPACs are purportedly ar esult of the steric hindrance imposed on the DPAC moiety,which, upon optical excitation, undergoes structural planarization resulting in al arge Stokes-shifted emission. By exploiting the resulting structure-dependent emission properties,d iverse applications of PISP molecules have been reported, including white-light generation, [3] hydrolysis, [2d] and sensing for self-assembled metallacycles. [2a] To generalize,a sw ell as extend the scope of PISP compounds,i nt his study,anew class of compounds bearing phenothiazine was synthesized, including 10-phenyl-10Hphenothiazine (NAS), 7-phenyl-7H-benzo[c]phenothiazine (NAS-1), and 12-phenyl-12H-benzo[a]phenothiazine (NAS-2; Figure 1a). NAS-1 and NAS-2 are strategically designed to act as constitutional isomers,but are subject to different steric strains in the core chromophore benzophenothiazine.The aim of this study is twofold. Firstly,w ei ntend to explore if heterocyclic systems other than DAPC are able to undergo PISP,broadening its utility in chemistry.Secondly,byaccessing isomers with distinct steric strain, the mechanism of the structure-PISP relationship can be explored. Also,p henothiazines are emerging materials which have been recently reported to show persistently long phosphorescence suitable for potential applications in bioimaging. [4] As ar esult, NAS-2,w hich possesses am arkedly bent structure,undergoes prominent PISP,generalizing the mechanism of PISP governed by steric hindrance.Moreover,inthe solid state,u nlike the conventional stacking planar structure induced excimeric reaction, [5] the bent NAS-2 reveals anomalous excimer formation ...

Based on third-harmonic-generation (THG) microscopy and a k-means clustering algorithm, we developed a label-free imaging cytometry method to differentiate and determine the types of human leukocytes. According to the size and average intensity of cells in THG images, in a two-dimensional scatter plot, the neutrophils, monocytes, and lymphocytes in peripheral blood samples from healthy volunteers were clustered into three differentiable groups. Using these features in THG images, we could count the number of each of the three leukocyte types both in vitro and in vivo. The THG imaging-based counting results agreed well with conventional blood count results. In the future, we believe that the combination of this THG microscopy-based imaging cytometry approach with advanced texture analysis of sub-cellular features can differentiate and count more types of blood cells with smaller quantities of blood.

We demonstrate the construction of wavelength λ-ratiometric images that allow visualizing the distribution of microscopic dynamics within living cells and tissues by using the newly developed principle of fluorescence response. The bent-to-planar motion in the excited state of incorporated fluorescence probes leads to elongation of the π-delocalization, resulting in microviscosity-dependent but polarity-insensitive interplay between well-separated blue and red bands in emission spectra. This allows constructing the exceptionally contrasted images of cellular dynamics. Moreover, the application of probes with increased affinity toward biological membranes allowed detecting the differences in dynamics between the plasma membrane and intracellular membrane structures. Such λ-ratiometric microviscosity imaging was extended for mapping the living tissues and observing their inflammation-dependent changes.