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A fluorescent turn-on chemosensor (BA) was constructed by attaching bis(pyridin-2-ylmethyl)-amine (DPA) unit to the BODIPY scaffold. It can give a prominent green/yellow fluorescent response selectivity with each of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+. The 1:1 stoichiometry of BA and metal ions was drawn from the analysis of Job’s plot. The limit detection of BA in recognition of Zn2+/Hg2+/Cd2+/Ca2+/Mn2+/Pb2+/Al3+ is ranged in 50.8-146.6 nM. There exists a linear relationship between the fluorescence intensity and concentration of metal ions (Zn2+: 4-15 µM). The mechanism of fluorescence signal “turn-on” is based on the photo induced transfer (PET) in the excited state of BA. The coordinated metal ions significantly weakened the electron-donating ability nitrogen atom in DPA, thus recovering the emission character of BODIPY. The substituted group at the phenyl ring in meso-position of BODIPY scaffold determines the recognizable list of metal ions. [ABSTRACT FROM AUTHOR]

[Display omitted] • Chemosensor was configured by attaching responsive group, diaminomaleonitrile, to BODIPY scaffold. • Cu2+ can be selectively recognized on a 2-s time-scale. • The recognition mechanism is based on the Cu2+ induced intramolecular oxidative cyclization of γ-aminoimine. • The absolute fluorescence quantum yield of BD + Cu2+ is determined to be 98%, attributing to the formation of dicarbonitrile substituted imidazole ring. A highly fluorescent Cu2+-responsive sensor, 2-amino-3-(BODIPYmethyleneamino)maleonitrile (BD) was constructed by attaching diaminomaleonitrile to a BODIPY scaffold. Cu2+ can be selectively recognized on a 2-s time-scale by way of fluorescence emission. When Cu2+ and BD coexist in solution, typical BODIPY emission was observed and the emission intensity could be increased to 334 times that of the blank dye solution. The mechanism of fluorescence increase is based on the generation of highly fluorescent species by Cu2+-triggered oxidative cyclization of the attached diaminomaleonitrile. The absolute fluorescence quantum yield (AFQY) of the cyclization product is 98% determined by integrating sphere. The highly emissive character can be attributed to the imidazole ring and dicarbonitrile on the BODIPY scaffold. It surpasses the meso -phenyl substituted analogue in AFQY and detection limits (DL). The specific Cu2+ recognition behavior was also validated in Hela cells with high-contrast fluorescence images. [ABSTRACT FROM AUTHOR]

A heavy metals sensor (2-N,N-bis(pyridin-2-ylmethyl)methanamine-BODIPY, DB) for the recognition of Pb2+, Ba2+, Cr2+, Cd2+, Hg2+, Sn2+, and Zn2+ was developed by anchoring (bis(pyridin-2-ylmethyl)amine) DPA unit to the BODIPY framework. It exhibited excellent sensitivity and selectivity against other competent metal ions. The stoichiometry of DB and metal ions were determined to be 1:1. The limit of detection of DB toward Pb2+, Ba2+, Cr2+, Cd2+, Hg2+, Sn2+, and Zn2+ was ranged from 60.07 to 89.37 nM. Photo induced transfer (PET) leads to the weak emission of BODIPY unit. When metal ions anchored with DPA, PET was blocked due to the weak electron donating ability of N in DPA to BODIPY and the highly emissive character of BODIPY was recovered, establishing a fluorescence switch. [ABSTRACT FROM AUTHOR]

A BODIPY based with perimidine attached derivative was developed and characterized. It was efficiently synthesized by condensation between aldehyde sited at β-position of BODIPY and 1,8-diamino-naphthalene. Owing to the electron-donor effect of N in heterocycle, emission was quenched completely. Upon protonation of N, the solution exhibited dramatic emission enhancement with emission peak locating at 510 nm, which is estimated to be 275-fold of initial emission. With OH−addition, it could be reverted to the emission to non-emisison state again and establish a fluorescence switch. The underlying mechanism of fluorescence “off-on” is based on the intramolecular PET, which was attested by quantum chemistry calculation approach. [ABSTRACT FROM PUBLISHER]

A new red-fluorescent BODIPY derivative is designed and synthesized, which is configured by attaching an electron-withdrawing unit 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF). By virtue of the strong electron-accepting nature of TCF unit, the compound BT exhibits a large red-shift both in absorption and emission. In contrast to parent BODIPY, the absorption shifted about 90 nm. And the emission maximum shifted to red region with the peak centered around 620 nm. The CIE coordinate and fluorescence decay data uncovered its emission character. Theoretical calculation of BT confirmed that the electron density was altered dramatically by TCF and lowered the energy gap between ground state. The character of HOMO/LUMO distribution is well in agreement with that of experimental value. [ABSTRACT FROM PUBLISHER]

A probe for recognition of IIB (Zn2+, Cd2+, and Hg2+) and VIB (Cr3+) was developed based on the framework of BODIPY. The probe was synthesized by attaching DPA to 4-position of BODIPY. It exhibited excellent sensitivity and selectivity function for the IIB and VIB metal ions with 1:1 stoichiometry in acetonitrile solution. The limit of detection of Zn2+, Cd2+, Hg2+, and Cr3+were obtained by fluorescence “turn-on” and ranged from 20.6 to 23.1 nM. Other metal cations did not interfere with the emission sensing of Zn2+, Cd2+, Hg2+, and Cr3+. The underlying mechanism of fluorescence “turn-on” is based on the intramolecular PET, which controlled the fluorescence “on” or “off.” [ABSTRACT FROM AUTHOR]

A specific Cu2+ sensor, 2-amino-3-(BODIPYmethyleneamino)maleonitrile (BDM), was established by a simple dehydration between BODIPY and diaminomaleonitrile. Cu2+ could be recognized by BDM over other competing metal ions in acetonitrile with distinct fluorescence emission signal response. Upon the addition of Cu2+ to BDM in acetonitrile, the maximum absorption at approximately 530 nm on the longer wavelength side was quenched, and the emission at 530 nm was ignited simultaneously. The fluorescence intensity enhancement could reach a maximum of 204 times the intensity of the BDM blank solution. The fluorescence "off-on" effect is established according to the Cu2+-induced fast intramolecular oxidative cyclization reaction, which could be deduced from the formation of an imidazole ring appended to the cyclization product (2-BODIPY-1 H -imidazole-4,5-dicarbonitrile, BMC). Single-crystal structure analysis of the sensor BDM and cyclization product BMC further demonstrated this oxidative cyclization. Finally, the Cu2+ recognition property of BDM was validated in SiHa cells and living zebrafish. Additionally, the blood-brain barrier of the zebrafish can be penetrated by the BDM dye and the neuron cells in the brain were stained. Unlabelled Image • Intramolecular oxidative cyclization reaction based sensor was established. • Single crystal structure analysis was also demonstrated. • Sensing property was validated in Siha cells and living vertebrate model, zebrafish. [ABSTRACT FROM AUTHOR]