We report the facile preparation of photoresponsive AA/BB supramolecular polymers comprising an E-stiff-stilbene bridged guest (E-G) and a disulfide-bridged bispillar[5]arene (H). The different assembly behaviours of Z-G and E-G with H were thoroughly investigated by 1H NMR, ROESY, DOSY and viscosity experiments, respectively. The 1 : 1 mixture of Z-G and H assembled into oligomers at 5–150 mM. In contrast, the 1 : 1 mixture of E-G and H assembled into AA/BB-type supramolecular polymers following a ring-chain polymerization mechanism. The formation and disassembly of the AA/BB supramolecular polymers were regulated by photoisomerization of stiff stilbene.

The bidirectional singlet–singlet and triplet–triplet energy transfer processes were observed for the first time within a noncovalent hydrogen-bonded module. For this purpose, 2-ureido-4[1H]-pyrimidinone quadruple hydrogen-bonds (UPy) functionalized BF2-chelated dipyrromethene (BODIPY-UPy) and iodinated BODIPY (I-BODIPY-UPy) were synthesized. These molecules formed energy donor–acceptor assembly through quadruple self-complementary hydrogen bonds, which demonstrated interesting photophysical properties. Spectroscopic studies in toluene solution revealed that selective excitation of BODIPY-UPy in the assembly resulted in efficient intra-assembly singlet energy transfer from excited BODIPY-UPy to I-BODIPY-UPy. This was followed by intersystem crossing of I-BODIPY-UPy from S1 to T1 and the backward triplet energy transfer from the I-BODIPY to BODIPY part. Time-resolved transient absorption spectroscopy confirmed that the triplet excited-state energy was distributed on both chromophores in the assembly. Density functional theory (DFT) calculations further validated the feasibility of energy transfer as well as two degenerate triplet states in the assembly. The present studies revealed that the bidirectional singlet–singlet and triplet–triplet energy transfer processes could be manipulated through the noncovalent quadruple hydrogen bonds. Studies on such a process in supramolecular assembly are of considerable importance in the elucidation of their possible function in natural photosystems and inspire applications in various fields such as luminescent materials, optoelectronic devices, photocatalysis, and photodynamic therapy.

•Dicyanoboron diketonates were synthesized and their optical properties were studied.•The emission of the dyes was extended to the deep red region.•The dyes exhibited high molar absorption coefficients and high photostability.A new class of dicyanoboron diketonates (B(CN)2) was synthesized and the photophysical properties were investigated. The B(CN)2 complexes exhibited high molar absorption coefficients, large Stokes shifts, high photostability and low cytotoxicity. Especially, the emission of the B(CN)2 extended into the deep red region. The extensive π conjugation and the presence of intramolecular charge transfer (ICT) transitions are responsible for their red-shifted emission. Their fluorescence are very sensitive to the polarity of the solvents. They are highly emissive in low polarity solvents, but weakly fluorescent in polar solvents. Cell imaging experiments demonstrated its potential application as a probe in bioorganisms due to its excellent imaging contrast. This strategy represents a facile approach to modulate the photophysical properties of dyes.We report a new class of dicyanoboron diketonates complexes which exhibit high molar absorption coefficients, large Stokes shifts, high photostability and low cytotoxicity.

We reported a new monofunctionalized pillar[5]arene bearing imidazolium moiety that formed stable [1]pseudorotaxane even at high concentration (100 mmol/L) in chloroform. The self-assembly was detailed investigated by multiple methods, including varying concentration 1H NMR, 2D COSY NMR, 2D NOESY NMR, viscosity measurements, 2D DOSY NMR, and HR-ESI-MS analysis. [1]Rotaxane was obtained efficiently through photo thiol-ene reaction which further confirmed the formation of [1]pseudorotaxane.A new monofunctionalized pillar[5]arene bearing imidazolium moiety that formed stable [1]pseudorotaxane even at high concentration (100 mmol/L) was reported. [1]Rotaxane was obtained efficiently through thiol-ene reaction from [1]pseudorotaxane which further confirmed the formation of [1]pseudorotaxane.

Herein we report the first example of a difluoroboron dibenzoyl based fluorescent probe for Cd2+ detection. The probe displays high selectivity and sensitivity toward Cd2+ over Zn2+ in aqueous solution under physiological conditions. Fluorescence imaging experiments demonstrate its potential application for detecting Cd2+ in living cells.

Herein we report the first example of a difluoroboron dibenzoyl based fluorescent probe for Cd2+ detection. The probe displays high selectivity and sensitivity toward Cd2+ over Zn2+ in aqueous solution under physiological conditions. Fluorescence imaging experiments demonstrate its potential application for detecting Cd2+ in living cells.