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Stimulus-induced in situ forming hydrogels possess the characteristics of easy management and minimal invasiveness via simple injection at target sites with a liquid and easy forming bulk gels. In the present study, a photoreactive monomer, N’-(2-nitrobenzyl)-N-acryloyl glycinamide (NBNAGA) was introduced to modify polyacrylamide (PAM) hydrogel preparation with stimuli responsiveness. Firstly, poly(acrylamide-co-N’-(2-nitrobenzyl)-N-acryloyl glycinamide), P(AM-co-NBNAGA), copolymer solution was prepared via reversible addition fragmentation chain transfer (RAFT) polymerization using the monomers mixture of AM, NBNAGA, and N,N’- methylene bis-acrylamide (BIS). The obtained polymer solution with viscous, transparent, and flowable appearance contained weak single hydrogen bonding and slight chemical crosslinking in a microscopic perspective. Secondly, without further purification, after irradiation using UV light at 365 nm, poly(acrylamide-co-N-acryloyl glycinamide) (P(AM-co-NAGA)) hydrogel conveniently in situ formed due to the cleavage of o-nitrobenzyl groups and the corresponding emergency of dual hydrogen bonding among “uncaged” dual amide moieties. P(AM-co-NAGA) hydrogel depicted both favorable temperature sensitivity and self-healing properties, then the heating induced in vitro release profiles of doxorubicin (DOX) was analyzed.

Novel organic/inorganic hybrid star polymer was prepared dually crosslinked within inner-core via divinylbenzene (DVB) and outer-surface via octafunctional polyhedral oligomeric silsesquioxane (POSS). Core cross-linked star polymers bearing dialkynyl-terminated polystyrene arms, (dialkynyl-PS)n-CCL, were synthesized at first by the atom transfer radical polymerization (ATRP) of DVB using α,α-dialkynyl-terminated PS macroinitiator, followed by the subsequent fractionation. Under high dilution conditions, (dialkynyl-PS)n-CCL was subjected to surface cross-linking with octa(3-azidopropyl) polyhedral oligomeric silsesquioxane, POSS-(N3)8, via click reaction, affording POSS-functionalized hybrid polymer doubly cross-linked within core and surface regions, SCL-(PS)n-CCL. FT-IR, 1H NMR, GPC, and elemental analysis results revealed that on average, the obtained hybrid polymer possesses a cross-linked PDVB inner core, ∼14 linear PS arms (the Mw per arm of 5.1 kDa), and ∼4-5 POSS moieties at outer surface. Differential scanning calorimetry (DSC) thermograms and thermogravimetric analysis (TGA) revealed that after surface cross-linking the thermal stability of SCL-(PS)n-CCL is considerably improved. This work provides a proof-of-concept example for the preparation of dually cross-linked hybrid star polymer, which represents a novel category of organic/inorganic composite materials with unique chain architectures.

Two novel similar structural coumarin-based fluorescent compounds L1 and L2 employing ether oxygen chain and 2 – pyridine unit had been prepared to explore the effect of structural adjustment on property. The prepared L2 through slightly adjusting structure of L1 exhibited the prominent fluorescence responses to Hg2+ and Cu2+ in H2O, which could monitor the corresponding metals ion in mitochondria of Hela cells, but L1 only recognized Hg2+ through turn-on fluorescence response in CH3OH/H2O, fluorescence co-localization studies illustrated that the L1 mainly located at lysosome. The recognition mechanism had been established by 1H NMR titration, Job’s plot, MAlDI-TOF mass spectrometry and single crystal structure. Bio-imaging experiments revealed that L1 and L2 could qualitatively monitor Hg2+ or Cu2+ in Hela cells and mouse kidney tissues.

Conventional probes are often difficult to observe apoptosis and autophagy at the same time. Herein, a series of small molecule multifunctional probes (L1-L6) were developed conveniently. Among, probes L1-L2 located in the mitochondria and L3 located in the lysosome in live cells, probes L4-L5 targeting mitochondria and L6 targeting lysosomes in living cells were further developed as a comparison. The experiment results of cells apoptosis showed that L1-L3 could immigrate to nucleolus, but L4-L6 did not due to the increased lipotropy. Significantly, fluorescence microscopy images showed that L2 could accumulate in the autophagic vacuoles when autophagy was activated, which gradually fused with lysosomes to form autolysosomes with increase of autophagy vacuoles. The results provided a beneficial reference for further preparing multifunctional fluorescence probe for monitoring apoptosis and autophagy.

Three new anthryl Schiff base derivatives containing a similar molecular structure were synthesized through a simple method and their fluorescent properties were investigated in detail. Among these, compound 1 displayed an aggregation-induced emission (AIE) feature, 2 exhibited an aggregation-induced emission enhancement (AIEE) property, while 3 showed aggregation-caused quenching (ACQ) behavior. Single-crystal structure and theoretical calculation analysis show that the larger conjugation and the existence of multiple intra- and intermolecular interactions restricts the intramolecular vibration and rotation, which benefit the emission in the condensed state, while the tight dimer structure and intramolecular torsional motion induce fluorescence quenching. Moreover, compound 2 can be utilized as fluorescence on–off type sensor for Cu2+ in methanol–H2O (4/1, v/v, pH 7.2) HEPES buffer solution, as well as fluorescence off–on type sensor for Zn2+ in pure methanol solution. The 2 : 1 ligand-to-metal coordination pattern of the 2-Cu2+ and 2-Zn2+ were calculated through a Job's plot, and were further confirmed by X-ray crystal structures of complexes 2-CuBr2 and 2-ZnCl2. In addition, 2 also exhibits a piezofluorochromic characteristic.

In this paper, a novel easily available off–on fluorescent and colorimetric probe based on triphenylamine-isophorone-based Schiff base was synthesized and characterized by 1 H NMR, 13 C NMR, MS, FTIR. A comprehensive analysis on recognition ability of the target product toward metal ions was conducted by ultraviolet absorption and fluorescence emission spectra. Results showed that the target product was stable in pH 5–9, and had effectively selective and sensitive recognition toward Cu 2+ in acetonitrile, with no significant interference of other competitive metal ions. The limit of detection of this probe was calculated as low as 1.568 × 10 −6 M for Cu 2+ .

A coumarin-based colorimetric and fluorescence off–on probe (L) containing diaminomaleonitrile unit was synthesized. The probe can detect Cu2+ in acetonitrile solution with high sensitivity and selectivity. The single crystal structures of probe L and L-Cu2+ complex showed that Cu2+ played dual roles of coordination center and catalyst that catalyzed the ring-closing of diaminomaleonitrile moiety in the recognition process based on addition reaction. Moreover, this probe can successfully detect Cu2+ in living cells.

Two novel soluble chemosensors (L1, L2) modified by aza-crown ether groups have been synthesized by one-step facile reaction. The chemosensors were fully characterized by IR, 1H NMR, 13C NMR and MS spectra. The recognition abilities of two sensors with a range of metal ions were evaluated. The results showed that L1 was a specialized sensor for Cu2+ and L2 was a multi-functional sensor being able to recognize Al3+ and Cr3+ via two different optical behaviors, which demonstrated the subtle structural changes of sensors can have a remarkable effect on recognizing metal ions.

Three new Schiff base derivatives possessing vagarious blue aggregation-induced emission (AIE) characteristics in tetrahydrofuran (THF)–water were synthesized. Their photophysical properties in solution, aqueous suspension, film and crystalline states, along with their relationships, were comparatively investigated. The crystallographic data for dye 1 and dye 3 indicated that the existence of multiple intermolecular hydrogen bonding interactions restricted intramolecular vibration and rotation. Moreover, the sizes and growth processes of particles with different water fractions were studied using a scanning electron microscope (SEM) and dynamic light scattering (DLS). The results showed that the small homogeneous particles, assembled in an ordered fashion with appropriate water contents, exhibited distinct AIE behavior. Moreover, in a THF–H2O (4 : 1, v/v) solution of HEPES (20 mM) buffer, dye 2 showed fluorescence turn-on sensing towards Cr3+ and Al3+via chelation enhanced fluorescence (CHEF). The 2 : 1 stoichiometries of the sensor complexes (dye 2–Cr3+ and dye 2–Al3+) were calculated from Job plots based on fluorescence titrations.

A new Schiff-base family containing [4-(1H-benzimidazole-2-yl)-phenyl]-bis-(4-ethoxy-phenyl)-amine has been synthesized through a condensation reaction. All the derivatives possess properties of aggregation-induced and crystallization-enhanced emission (AIE and CEE), which show time-dependent characteristics at a concentration of 10 μM and are studied in detail by scanning electron microscope (SEM) and transmission electron microscope (TEM). Different aggregation forms and the growth of crystals of the compounds, could be responsible for the notably different degrees of fluorescence enhancement.

Two ligands, 2-{5,5-dimethyl-3-[2-(pyridin-3-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L1) and 2-{5,5-dimethyl-3-[2-(pyridin-2-yl)-ethenyl]cyclohex-2-enylidene}propanedinitrile (L2), were synthesized. By reaction of mercury thiocyanate with L1 and L2, respectively, coordination polymers [Hg(L1)(μ1,3-SCN)2]n (1), [Hg(L1)2(μ1,3-SCN)2]n (2), and [Hg(L2)(μ1,3-SCN)(SCN)]n (3) with different structures and topologies were obtained. In 1, the thiocyanate shows μ1,3-SCN bridging coordination, and adjacent Hg(II) ions are bridged by two μ1,3-SCN ions to form an infinite chain with the remaining position of five-coordinate Hg(II) occupied by L1. In 2, the thiocyanate has the same coordination as 1. However, Hg(II) has octahedral coordination with two L1 involved in coordination. An unusual feature of 3 is the presence of two types of thiocyanates, one has a S-terminal ligand and the other has a μ1,3-SCN bridge. The mercury(II) in 3 is four-coordinated by L2 and three thiocyanates. Luminescent properties an...

A series of new cadmium complexes (dyes 1–5) were obtained by assembly of the donor–bridge–acceptor (D–π–A)-type ligand (L: 4′-(4-[4-(imidazole)styryl]phenyl) 2,2′ : 6′,2″-terpyridine) with CdX2 (X=Cl, Br, I, NCS, ClO4), in which dye 3 was characterized by single crystal X-ray diffraction. Various weak interactions, including hydrogen bonds (C–H⋯N, C–H⋯X) and π–π interactions, played significant roles in the final topological structures. Linear and non-linear optical properties of ligand and the complexes were investigated. The two-photon absorption cross-section of these complexes are larger than that of ligand with maximum values of 577 GM (dye 1), 242 GM (dye 2), 171 GM (dye 3), 326 GM (dye 4), and 215 GM (dye 5) in N,N-dimethylformamide.

A new series of D–π–A type two-photon absorption (2PA) dyes (1–4) based on imidazo[4,5-f]1,10-phenanthroline have been synthesized and their photophysical properties have been systematically investigated. These dyes showed obvious positive solvatochromic effects mainly due to intramolecular charge transfer (ICT). The two-photon absorption (2PA) cross-section values measured by two-photon excited fluorescence (TPEF) were determined to be 1232 GM and 4752 GM for dye 3 and dye 4, while dyes 1 and 2 do not display 2PA activity. These results demonstrate that their 2PA cross section values (σ) increase with increasing donor/acceptor (D/A) strength of the corresponding molecule. The results also imply that the replacement of the tetrazol group with the aza-crown-ether group results in an opposite charge transfer direction, which has been verified by density functional theory (DFT) calculations. In addition, a two-photon fluorescence cell imaging experiment proved the suitability of dye 3 for this potential application .

Fibrous nanoaggregates of a new benzoxazole-based derivative have been reported. This derivative exhibits not only H-aggregates but also strong yellow fluorescence, which is different from the traditional understanding of H-aggregates.

Five triphenylamine containing benzimidazole derivatives (a1–a5) with different D/A groups (D and A stand for donor and acceptor, respectively), conjugation length or configuration were designed and synthesized. The one- and two-photon spectroscopic properties of these molecules were studied. All of these compounds have amazing fluorescence quantum yields in the range of 0.39–0.61. Besides, for a1–a5, the λem (emission maximum wavelength of one- and two-photons) are only dominated by the D/A groups, and the conjugation length is irrelevant, implying that the molecular rotation is in the excited-state. To better explain this phenomenon, the structure–property relationships of a1–a5, especially the molecular rotation in the excited-state, have been discussed in detail, and were identified by density functional theory calculations. Furthermore, four azo-heterocycle containing benzimidazole derivatives, which have weak electron-donating ability, were synthesized and discussed as a comparison. Finally, considering their optical action, cytotoxicity and solubility, a1, a2 and a4 were chosen for bio-imaging. The results show that the small molecule a2 is the best candidate for one-photon excited fluorescence and two-photon excited fluorescence imaging.