Chemical and Electrochemical Dimerization of BODIPY Compounds: Electrogenerated Chemiluminescent Detection of Dimer Formation

Abstract

The electrochemistry of several difluoroboradiaza-s-indacene (BODIPY) compounds lacking substituent groups in the meso (8)- and/or 3 (α)-positions was investigated. Chemical and electrochemical dimerization was demonstrated, and the dimerization depended on the character of substitution. The chemical dimerization was achieved by oxidative coupling using FeCl(3) in CH(2)Cl(2) at 0 °C. The electrochemical dimerization proceeded via anodic oxidation to the radical cation and monitored by both cyclic voltammetry (CV) and electrogenerated chemiluminescence (ECL). An available open 3-position was important for the formation of the dimer. The resulting 3,3'-dimer produced a second peak in the CV oxidation and also the appearance of a longer wavelength ECL peak at 656 nm, which is considerably shifted from the parent peak at 532 nm. No dimerization was seen for BODIPY molecules in which only the meso 8-position was unsubstituted, either by chemical or electrochemical means, demonstrating that dimerization occurs at position 3.

Thiocyanation of BODIPY dyes and their conversion to thioalkylated derivatives

“…The planned reaction occurred when the amounts of oxone and ammonium thiocyanate were increased (Table 4), but the insertion of a second thiocyanate group seemed to be more difficult. Even when a large excess of oxone and ammonium thiocyanate was used, we could not observe full conversion, and a mixture of monothiocyanato (13) and dithiocyanato (19) BODIPYs were obtained. Additionally, although heating seems to accelerate the reaction, it also lowers the overall yields.…”

“…5 To the best of our knowledge, thiocyanatosubstituted boron dipyrrins have not been previously reported, although they can be considered starting materials for BODIPY sulfides. [6][7][8][9][10] For this study, ten BODIPYs (Table 1) were synthesized using established procedures [11][12][13][14][15][16][17][18] and were used as starting materials for further reactions. …”

Electrochemistry and electrogenerated chemiluminescence of thiophene and fluorene oligomers. Benzoyl peroxide as a coreactant for oligomerization of thiophene dimers

“…Formation of the electrochemical products monitored by ECL has been reported earlier for the reductive dimerization of fluoranthene in the presence of persulfate and for the unblocked BODIPY dyes. 43,44 The mechanism of the activity for benzoyl peroxide ECL can take place as follows: This mechanism is radical-substrate coupling (rsc). 81 The other mechanism including radical-radical coupling (rrc) is also possible: …”

Imaging Analysis Based on Electrogenerated Chemiluminescence

“…Due to the high fluorescence quantum yields and stable radical cations and anions in aprotic media, ECL generation by aromatic hydrocarbons such as rubrene and 9,10-diphenylanthracene (DPA) has been studied in detail by Hercules and Bard et al in the mid-1960s [8][9][10][11]. In addition, other organic emitters including acridinium esters [12], polymers [13][14][15], siloles [16], and boron-dipyrromethene (BODIPY) dyes [17][18][19][20][21] have also been extensively investigated. (ii) Inorganic systems: in 1960s and 1970s, ECL as a novel photochemical and electrochemical phenomenon has aroused much interest of investigation, and a variety of compounds, complexes, and clusters have been studied.…”