A Highly Selective and Sensitive Fluorescent Turn-Off Probe for Cu2+ Based on a Guanidine Derivative

Abstract

A new highly selective and sensitive fluorescent probe for Cu2+, N-n-butyl-4-(1′-cyclooctene-1′,3′,6′-triazole)-1,8-naphthalimide (L), was synthesized and evaluated. The structure of compound L was characterized via IR, 1H-NMR, 13C-NMR and HRMS. The fluorescent probe was quenched by Cu2+ with a 1:1 binding ratio and behaved as a “turn-off” sensor. An efficient and sensitive spectrofluorometric method was developed for detecting and estimating trace levels of Cu2+ in EtOH/H2O. The ligand exhibited excitation and emission maxima at 447 and 518 nm, respectively. The equilibrium binding constant of the ligand with Cu2+ was 1.57 × 104 M−1, as calculated using the Stern-Volmer equation. Ligand L is stable and can be used to detect Cu2+ in the range of pH from 7 to 12. The sensor responded to Cu2+ rapidly and a large number of coexisting ions showed almost no obvious interference with the detection.

Synthesis and Fluorescent Property Study of Novel 1,8-Naphthalimide-Based Chemosensors

“…As shown in Scheme 2 , the mono- and di-substituted 1,8-naphthalimide esters were synthesized via three steps. Although many efforts have been made to prepare 1,8-naphthalimide derivatives with different substitutions at position 4 [ 1 , 9 , 10 , 24 , 25 , 26 , 27 , 28 ], this is the first attempt to synthesize mono- and di-substituted 1,8-naphthalimide esters simultaneously at position 4. N -n-Butyl-4-bromo-1,8-naphthalimide was prepared by the convenient substitution of 4-bromo-1,8-naphtalic anhydride with n-butyl amine.…”

“…N -n-Butyl-4-bromo-1,8-naphthalimide was prepared by modifying a previously reported procedure [ 24 ] to obtain an improved yield of 84%. 4-Bromo-1,8-naphthalic anhydride (58 mmol, 16.1 g) and n-butylamine (60 mmol, 4.4 g) were heated under reflux in ethanol (250 mL) with vigorous stirring for 12 h under N 2 .…”

A novel hydrophilic fluorescent probe for Cu2+ detection and imaging in HeLa cells

“…[24][25][26] These methods require complicated preparation procedures, expensive instruments and trained professional technicians. 27 Recently, uorescent probes have gained attention due to several notable advantages, including high sensitivity, high specicity, good biocompatibility, simplied operation, and minimal invasiveness. [28][29][30][31] Many recent reports describe excellent uorescent sensors for detecting Cu 2+ .…”

A new 1,8-naphthalimide-based fluorescent “turn-off” sensor for detecting Cu2+ and sensing mechanisms

“…23 As a result of this, derivatives of 1,8-naphthalimide have been successfully utilized in the production of fluorescent whitening agents, liquid crystal displays, fluorescent dyes, laser-active media, electroluminescent materials, photoconductive materials, and fluorescent switches and sensors. [24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39] Until now, many excellent fluorescent sensors based on naphthalimide and its derivatives for detection of Cu II have been reported, [40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] but most were not sensitive enough to determine low concentration levels of Cu II and only function in organic solvents, with only a very few examples working in aqueous media. [56][57][58][59] Many copper compounds that coordinate with naphthalimide and its derivatives have been reported and their structures have been determined, but few have been used to explain the relationship between structure and fluorescence quenching mechanisms.…”