This review focuses on classifying different types of long wavelength absorbing BODIPY dyes based on the wide range of structural modification methods that have been adopted, and on tabulating their ...spectral and photophysical properties. The structure-property relationships are analyzed in depth with reference to molecular modeling calculations, so that the effectiveness of the different structural modification strategies for shifting the main BODIPY spectral bands to longer wavelengths can be readily compared, along with their effects on the fluorescence quantum yield (ΦF) values. This should facilitate the future rational design of red/NIR region BODIPY dyes for a wide range of different applications.
Abstract
Acid taste, evoked mainly by protons (H
+
), is a core taste modality for many organisms. The hedonic valence of acid taste is bidirectional: animals prefer slightly but avoid highly acidic ...foods. However, how animals discriminate low from high acidity remains poorly understood. To explore the taste perception of acid, we use the fruit fly as a model organism. We find that flies employ two competing taste sensory pathways to detect low and high acidity, and the relative degree of activation of each determines either attractive or aversive responses. Moreover, we establish one member of the fly Otopetrin family, Otopetrin-like a (OtopLa), as a proton channel dedicated to the gustatory detection of acid. OtopLa defines a unique subset of gustatory receptor neurons and is selectively required for attractive rather than aversive taste responses. Loss of
otopla
causes flies to reject normally attractive low-acid foods. Therefore, the identification of OtopLa as a low-acid sensor firmly supports our competition model of acid taste sensation. Altogether, we have discovered a binary acid-sensing mechanism that may be evolutionarily conserved between insects and mammals.
The Georgia Tech Library Public Services Department proposed to expand the number of staffed service points throughout the Library to increase coverage and service. The proposal was well-received by ...Library leadership and earned priority placement in the Library's annual budget request. The theoretical underpinning for this reception is an adaptation of Kingdon's three streams framework of public policy adapted to internal policy work: namely, that success in internal requests requires the same confluence of problem, policy, and politics to open a window of opportunity to place the issue on the agenda of those who make decisions.
This study describes the adsorption behavior of organic inhibitors at the aluminum-HCl solution interface and their corrosion inhibition performance. The organic inhibitors employed are: 4-(benzo ...dthiazol-2ylthio)phthalonitrile (BTThio) and tetrakis(benzodthiazol-2-yl-thio)phthalo- cyaninatogallium(III) chloride (ClGaBTThioPc). The corrosion behavior of these inhibitors is investigated using electrochemical and computational techniques. Open circuit potential results reveal predominant cathodic character for the mechanism of aluminum corrosion inhibition by the inhibitors. Inhibition efficiency values from potentiodynamic polarization measurements increase from 46.9 to 70.8% for BTThio and 59.7 to 81.0% for ClGaBTThioPc within the concentration range of 2 to 10 μM. Scanning electron microscopy (SEM) measurements reveal protection of the metal surface from acid attack, in the presence of the inhibitors and energy dispersive X-ray (EDX) measurements show that the most probable way by which the inhibitors protect the metal surface would be by shielding it from the corrosion attacks of Cl
from the acid. Quantum chemical parameters corroborate well with experimental findings.
A series of tetraarylchlorins with 3-methoxy-, 4-hydroxy- and 3-methoxy-4-hydroxyphenyl
-aryl rings (
-
-Chl) and their Sn(IV) complexes (
-
-SnChl) were synthesized and characterized so that their ...potential utility as photosensitizer dyes for use in photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) can be assessed. The photophysicochemical properties of the dyes were assessed prior to in vitro PDT activity studies against MCF-7 breast cancer cells through irradiation with Thorlabs 625 or 660 nm LED for 20 min (240 or 280 mW·cm
). PACT activity studies were performed against both planktonic bacteria and biofilms of Gram-(+)
and Gram-(-)
upon irradiation with Thorlabs 625 and 660 nm LEDs for 75 min. The heavy atom effect of the Sn(IV) ion results in relatively high singlet oxygen quantum yield values of 0.69-0.71 for
-
-SnChl. Relatively low IC
values between 1.1-4.1 and 3.8-9.4 µM were obtained for the
-
-SnChl series with the Thorlabs 660 and 625 nm LEDs, respectively, during the PDT activity studies.
-
-SnChl were also found to exhibit significant PACT activity against planktonic
and
with Log
reduction values of 7.65 and >3.0, respectively. The results demonstrate that the Sn(IV) complexes of tetraarylchlorins merit further in depth study as photosensitizers in biomedical applications.
Magnetic circular dichroism (MCD) spectroscopy has proven invaluable in the assignment of the optical spectra of the porphyrinoids over the last 40 years. Recently, with new power of the DFT ...theoretical treatments available routinely, the assignment of porphyrinoid spectra has become an important factor in the correct interpretation of the electronic structure predicted by the calculations. In this review, we have described in detail the formalism required to use the MCD technique to probe the electronic structure of porphyrinoid complexes. We begin with a detailed description of the optical background to the technique; continue by describing the current theoretical interpretation of the spectral morphology, and end by describing the analysis of the MCD spectral data for a number of porphyrins and phthalocyanines.
Two near-infrared (NIR) absorbing di(thien-2-nyl)-di(dimethylanilino)azaBODIPY dyes
and
were synthesized and characterized that differ depending on whether the dimethylaniline substituents are ...introduced at the 3,5- or 1,7-positions of the azaBODIPY core. The main spectral bands lie at 824 and 790 nm, respectively, in CH
Cl
. The effect of substituent position on the photophysical and pH sensing properties was analyzed through a comparison of the optical properties with the results of time-dependent density functional theory (TD-DFT) calculations. Protonation of the dimethylamino nitrogen atoms eliminates the intramolecular charge transfer properties of these compounds, and this results in a marked blue-shift of the main absorption bands to 696 and 730 nm, respectively, in CH
Cl
, and a fluorescence "turn-on" effect in the NIR region. The pH dependence studies reveal that the pK
values of the non-protonated
and
molecules are ca. 6.9 (±0.05) and 7.3 (±0.05), respectively, while that of the monoprotonated species for both dyes is ca. 1.4 (±0.05) making them potentially suitable for use as colorimetric pH indicators under highly acidic conditions.
A boron-dipyrromethene (BODIPY) dye containing a styryl substituent with a hydroxyl and nitro group, 1a, exhibits a 'turn-on' fluorescence response for hypoxic cells. The presence of the ...electron-withdrawing nitro group results in a highly efficient nonradiative decay of the S1 state, and hence a recovery of fluorescence intensity when nitro reduction occurs under hypoxic conditions.
The synthesis and properties of phosphorus(V) 5,10,15-tris(4-methoxycarbonylphenyl)corrole (1) have been investigated, and its potential utility for bioimaging applications in living cells has been ...explored. As would normally be anticipated for corrole complexes, the intensity of the Q(0,0) bands of 1 is greater than those of comparable phosphorus(V) tetraphenylporphyrins, but the ΦF values (0.25 for 1) are found to be comparable. A detailed analysis of the electronic structure of the complex was carried out by comparing electronic absorption and MCD spectral data to the results of TD-DFT calculations. The meso-aryl substituents, which enhance the lipophilicity of 1 and hence result in its localization in intracellular membranes during HeLa cell experiments, are predicted to result in a narrowing of the HOMO-LUMO gap and hence a red shift of the Q(0,0) bands toward the optical window in biological tissues.
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