Ground-state conformers enable bright single-fluorophore ratiometric thermometers with positive temperature coefficients

Abstract

A pseudo-rigid fluorophore with multiple conformers enables highly reliable single-fluorophore ratiometric temperature sensing.

Regioisomeric BODIPY Benzodithiophene Dyads and Triads with Tunable Red Emission as Ratiometric Temperature and Viscosity Sensors

“…Ratiometric analysis of temperature‐dependent emission is possible when one emission band changes with temperature while the other band remains unchanged or changes negligibly with temperature . The plot of ratio of intensities with temperature can be fitted with linear, exponential, or polynomial functions to obtain temperature coefficients and sensitivities of such molecular thermometers. Since temperature‐dependent emission of p ‐AD and p ‐ADA in different solvents revealed pronounced temperature‐dependent intensity changes in the TICT band ( I 2 ) while the LE/BDT emission band remained relatively unchanged ( I 1 ), ratiometric analyses of these data were performed.…”

“…Notably, rotors with positive temperature coefficients in this context are extremely desirable because the increase in emission intensities with temperature can significantly suppress background interference at high temperatures and thus are advantageous for sensing/imaging purposes . Interestingly, however, rotors showing positive temperature coefficients are rather few …”

“…[17] TICT rotors are promising viscosity probes because they exhibit emission enhancement due to restricted intramolecular rotationinsolvents of increasingv iscosity. [10,11,[18][19][20] Examples of ratiometric temperature and/or viscosity [8,11] sensors based on TICT rotors involvef luorophores such as tetraphenylethylenes (TPE), [4] indocyanines, [10,21] porphyrins, [22] 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY), [23][24][25][26][27] arylboranes, [28] N,N-dimethylaniline based compounds, [29] and many others. [25,26,[30][31][32][33][34][35] Luminescent thermometers based on molecular rotors are being intensively investigated for temperature sensing of cellular microenviron-ments as well as of microfluidic devices.…”

“…[29] Interestingly,h owever,r otors showing positive temperature coefficients are ratherfew. [28,29,49,51,52] Recently,w er eported an acceptor-donor-acceptor (p-ADA; Figure 1) type triad rotor consisting of BODIPY acceptor and benzodithiophene (BDT) donor that showede fficient TICTwith Stokes shift of ca. 194 nm (red em.…”

Latest Trends in Temperature Sensing by Molecular Probes

“…Another common method for avoiding the concentration dependence of intensity‐based temperature probes is to track changes in the emission wavelength maximum. A molecule's emission wavelength can be impacted by temperature due to conformational changes in the molecule, aggregation, or activation of alternative vibrational bands or spin states . One molecule that exhibits conformational changes upon heating is dipyren‐1‐yl(2,4,6‐triisopropylphenyl)‐borane (Figure , structure 22 ) …”