Fluorinated Boron‐Dipyrromethene (BODIPY) Dyes: Bright and Versatile Probes for Surface Analysis

Abstract

A family of bright boron-dipyrromethene-type fluorophores with a high number of fluorine atoms (F-BODIPYs) has been developed and characterized by X-ray crystallography and optical spectroscopy. The introduction of 3,5-bis(trifluoromethyl)phenyl and pentafluorophenyl moieties significantly enhances the photostability of such dyes, yielding for instance photostable near-infrared (NIR) fluorophores that show emission maxima>750 nm, when the BODIPY’s π system is extended with two (dimethylamino)styryl and (dimethylamino)naphthastyryl moieties, or green-emitting BODIPYs with fluorescence quantum yields of unity. When equipped with a suitable group that selectively reacts for instance with amines, F-BODIPYs can be used as potent dual labels for the quantification of primary amino groups on surfaces by X-ray photoelectron spectroscopy (XPS) and fluorescence, two powerful yet complementary tools for the analysis of organic surface functional groups. The advantage of reactive F-BODIPYs is that they allow a fast and non-destructive mapping of the labelled supports with conventional fluorescence scanners and a subsequent quantification of selected areas of the same sample by the potentially traceable XPS technique. The performance is exemplarily shown here for the assessment of the amino group density on SiO2 supports, one of the most common reactive silica supports, in particular, for standard microarray applications.

Multimode Surface Functional Group Determination: Combining Steady-State and Time-Resolved Fluorescence with X-ray Photoelectron Spectroscopy and Absorption Measurements for Absolute Quantification

“…The dynamic range of fluorometric methods is usually limited by effects of self-quenching at higher loadings, resulting in a deviation from linearity or even a reduction in the measured intensity. [22][23][24] The latter is not easily identifiable with commonly employed intensity-based (steady-state) instrumentation and can lead to an underestimation of surface functional groups. To account for such false negative results, different optical techniques like time-resolved fluorescence and absorption measurements need to be employed.…”

Structural modification strategies for the rational design of red/NIR region BODIPYs

“…Additionally, weaker broad absorption bands at shorter wavelengths can be assigned to S 0 −S n (n ≥ 2) transitions. [75][76][77][78][79][80][81][82] When the BF 2 moiety is removed from the BODIPY structure, the structure is converted into the all-trans conformation and the chromophore is converted into a type of cyanine dye. Cyanine dyes undergo trans-cis isomerization upon electronic excitation, which quenches the fluorescence.…”

An analysis of the photophysical and optical limiting properties of a novel 1,3,5-tristyrylBODIPY dye

“…1 and Tables 1 and 2. Single crystal Xray structures that have been reported for 3styryl [60] and 3,5distyryl [61][62][63] BODIPY dyes have demonstrated that the transstyryl bonds shown in Scheme 1 for 3 are formed. The introduction of methylthio groups at the parapositions of the styryl groups provides scope for nanoparticle conjugation [64], and the mesomeric electron donating properties of the lone pairs on the sulfur atoms were expected to further enhance the red shift of the main spectral band [17].…”