A novel 1,8-naphthalimide-based Cu2+ ion fluorescent probe and its bioimaging application.

A new 1,8-naphthalimide-based Schiff base compound, named as (Z)-2-butyl-6-(((2-hydroxyphenyl)imino)methyl)-1H-benzo[de]isoquinoline-1,3(2H)-dione (BHBD), has been simply synthesized with high yields. BHBD can be employed as a "turn-on" fluorescent probe for Cu2+ ion with high sensitivity, high selectivity and relatively low detection limit (0.48 × 10-6 M). The fluorescence emission of BHBD is very weak in H2O/THF (v/v: 7/3) mixture, which is significantly enhanced after addition of Cu2+ ion. The proposed mechanism is verified by 1H NMR, Job's plot and TOF-MS experiments. Anti-interference experiment, cytotoxicity assay and pH influence results indicated that BHBD meets the requirements of bioimaging. Therefore, BHBD has been successfully applied in detecting Cu2+ ion in HeLa cells.

Synthesis, crystal structure and aggregation-induced emission of a new pyrene-based compound, 3,3-diphenyl-2-[4-(pyren-1-yl)phen-yl]acrylo-nitrile.

The title organic compound, C37H23N, crystallizing in the triclinic space group P [Formula: see text], has been designed, synthesized and characterized by single-crystal X-ray diffaction, MS, NMR and elemental analysis. There are alternating relatively strong and weak intermolecular π-π interactions between adjacent pyrene ring systems, forming a one-dimensional supramolecular structure. The compound is weakly fluorescent in THF solution, but it is highly emissive in the condensed phase, revealing distinct aggregation-induced emission (AIE) characteristics.

A series of 4,5,9,10-tetrahydropyrene-based tetraarylethenes: synthesis, structures and solid-state emission behavior.

By controlling the number of 4,5,9,10-tetrahydropyrene segments around the tetraarylethene core, a series of 4,5,9,10-tetrahydropyrene-based tetraarylethenes were synthesized and structurally characterized. An aggregation-induced emission (AIE) study indicated that all the compounds are AIE active: they are weak emitters in good solvents but highly emissive in the condensed phase, and hence are potential solid-state emitters. Their optical properties, electrochemical properties and theoretical calculations were investigated, and the results prove that the π-conjugation degree of these compounds increases with the increasing number of 4,5,9,10-tetrahydropyrene units. However, the fluorescence quantum yield in the solid state doesn't increase with increasing π-conjugation. We studied the reason for this by analyzing the crystal structures of some compounds, and proposed that the close degree of molecular packing in the solid state may be responsible for it. Loose packing of tetraarylethenes in the solid state can restrict the rotation of the aromatic rings but cannot constrain other non-radiative pathways efficiently, such as vibration, which leads to the unpredictable emission of the compounds.