Dimers of Dipyrrometheneboron Difluoride (BODIPY) with Light Spectroscopic Applications in Chemistry and Biology

Abstract

A ground-state dimer (denoted D(I)) exhibiting a strong absorption maximum at 477 nm (epsilon = 97 000 M(-1)cm(-1)) can form between adjacent BODIPY groups attached to mutant forms of the protein, plasminogen activator inhibitor type 1 (PAI-1). No fluorescence from excited D(I) was detected. A locally high concentration of BODIPY groups was also achieved by doping lipid phases (micelles, vesicles) with BODIPY-labeled lipids. In addition to an absorption band located at about 480 nm, a new weak absorption band is also observed at ca. 570 nm. Both bands are ascribed to the formation of BODIPY dimers of different conformation (D(I) and D(II)). Contrary to D(I) in PAI-1, the D(II) aggregates absorbing at 570 nm are emitting light observed as a broad band centered at about 630 nm. The integrated absorption band of D(I) is about twice that of the monomer, which is compatible with exciton coupling within a dimer. The Förster radius of electronic energy transfer between a BODIPY excited monomer and the ground-state dimer (D(I)()) is 57 +/- 2 A. A simple model of exciton coupling suggests that in D(I) two BODIPY groups are stacked on top of each other in a sandwich-like configuration with parallel electronic transition dipoles. For D(II) the model suggests that the S(0) --> S(1) transition dipoles are colinear. An explanation for the previously reported (J. Am. Chem. Soc. 1994, 116, 7801) exceptional light spectroscopic properties of BODIPY is also presented. These are ascribed to the extraordinary electric properties of the BODIPY chromophore. First, changes of the permanent electric dipole moment (Delta(mu) approximately -0.05 D) and polarizability (-26 x 10(-40) C m(2) V(-1)) between the ground and the first excited states are small. Second, the S(0) <--> S(1) electronic transition dipole moments are perpendicular to Delta(mu).

Real-time analysis of composite magnetic nanoparticle disassembly in vascular cells and biomimetic media

“…The increase in the labeled PLA fraction to 40% was found to cause a shift in the fluorescence pattern of MNP[don], revealing, in addition to the expected emission peak at 575 nm, a prominent new peak at 612 nm ( Fig. S4B), possibly as a result of the formation of a dimeric form of the fluorophore exhibiting a red-shifted spectrum, as described previously for another BODIPY derivative (20,21). This shift in the emission spectrum due to the denser packaging of the donor fluorophore in the MNP matrix increases the overlap with the BODIPY 630/650 acceptor excitation spectrum (Fig.…”

“…This complex exhibiting excitation and emission maxima at 565 nm and 612 nm, respectively, and presumably representing a dimer with red-shifted fluorescence (21) contributed to improving the sensitivity of the FRET-based degradation assay through participating in a chain of energy transfer events: BODIPY 558/568 → [BODIPY 558/568 ] 2 → BODIPY 630/650 . A similar energy transfer between the monomeric and dimeric forms of the fluorophore was demonstrated previously for another BODIPY derivative (20). The implementation of the multistep FRET phenomenon enabling the effective use of the unique photophysical properties of BODIPY for developing highly sensitive measurement techniques may be of relevance to a broad range of quantitative analytic applications.…”

Solvent and pH Dependent Fluorescent Properties of a Dimethylaminostyryl Borondipyrromethene Dye in Solution

“…In acidified acetonitrile, this produces the typical BODIPY-like narrow absorption and emission bands with a very high fluorescence yield. 5, [13][14][15][16][17][18][19][20][21][22][23] The absorption spectra of 1 in acetonitrile are shown as a function of pH in Figure 12a. The absorption spectra of 1 show a decrease of the absorbance band with a maximum at 597 nm with increasing HCl concentration (i.e., lower pH) and a simultaneous increase of the absorption at 553 nm.…”

“…12 BODIPY is a well-known fluorophore characterized by valuable properties such as high (photo)chemical stability and relatively high fluorescence quantum yields (often approaching 1.0) and absorption coefficients. 5, [13][14][15][16][17][18][19][20][21][22][23] Moreover, borondipyrromethene dyes are excitable with visible light, have narrow emission bandwidths with high peak intensities, and are amenable to structural modification.…”

New BODIPY lipid probes for fluorescence studies of membranes

“…The location and insertion depth of the Me 4 -BODIPY-8 fluorophore in unilamellar bilayer vesicles have been assessed by quenching with free iodide (SternVolmer analysis) as well as with iodolabeled phosphatidylcholines (parallax analysis) (17). The physical and spectral features of these new phosphatidylcholine probes, in their pure states and in mixtures with other lipids, have been characterized in both bilayer and monolayer model membrane systems to assess the occurrence of lipid-packing distortions caused by the fluorophore as well as concentrationdependent dimerization associated with the BODIPY family of fluorophores (18,19).…”