The following novel solvatochromic probes were synthesized: 2,6-dibromo-4-[(E)-2-(1-alkylpyridinium-4-yl)ethenyl] phenolate, where the alkyl groups are methyl, n-butyl, n-hexyl, and n-octyl, respectively. Solvatochromism of three of these probes (C(1), C(4), and C(8)) was studied in 36 protic and aprotic solvents. A modified linear solvation energy relationship has been applied to the data obtained at 25 degrees C. Correlation of (empirical) polarities with other solvent properties showed more dependence on lipophilicity than on basicity. A similar conclusion has been reached for a series of other solvatochromic indicators. Exceptions are those that carry acidic hydrogens, being biased toward solvent basicity. Thermosolvatochromism has been studied in mixtures of water with methanol, 1-propanol, acetonitrile, and DMSO. Thermosolvatochromic data have been treated according to a model that explicitly considers the presence in bulk solution of three "species": water, organic component, and solvent-water hydrogen-bonded aggregate. Solvation by the latter is favored over solvation by either of the two precursor solvents (aqueous DMSO is an exception). Temperature increase resulted in desolvation of the probes, due to concomitant decrease of the structures of the component solvents. The above-mentioned modified solvation equation has been successfully applied to solvatochromism in aqueous methanol and aqueous 1-propanol.

The question raised in the title has been answered by comparing the solvatochromism of two series of polarity probes, the lipophilicities of which were increased either by increasing the length of an alkyl group (R) attached to a fixed pyridine-based structure or through annelation (i.e., by fusing benzene rings onto a central pyridine-based structure). The following novel solvatochromic probes were synthesized:. The solvatochromic behavior of these probes, along with that of 2,6-dibromo-4-[(E)-2-(1-methylpyridinium-4-yl)ethenyl]phenolate (MePMBr 2 ) was analyzed in terms of increasing probe lipophilicity, through annelation. Values of the empirical solvent polarity scale [E T (MePMBr 2 )] in kcal mol -1 correlated linearly with E T (30), the corresponding values for the extensively employed probe 2,6-diphenyl-4-(2,4,6-triphenylpyridinium-1-yl)phenolate (RB). On the other hand, the nonlinear correlations of E T (MeQMBr 2 ) or E T (MeAMBr 2 ) with E T (30) are described by second-order polynomials. Possible reasons for this behavior include: i) self-aggregation of the probe, ii) photoinduced cis/trans isomerization of the dye, and iii) probe structure-and solvent-dependent contributions of the quinonoid and zwitterionic limiting formulas to the ground and excited states of the probe. We show that mechanisms (i) and (ii) are not operative under the experimental conditions employed; experimental evidence (NMR) and theoretical calculations are presented to support the conjec-

A novel solvatochromic probe—2,6‐dibromo‐4‐[(E)‐2‐(1‐butylquinolinium‐4‐yl)ethenyl] phenolate, BuQMBr2—has been synthesized and its properties examined. The quinoline‐based probe is soluble in more organic solvents than the parent merocyanine dye, 4‐[2‐(1‐methylpyridinium‐4‐yl)ethenyl] phenolate, and its pKa is lower by 3.7 units. Its solvatochromic data in binary mixtures of cyclohexane–n‐butanol showed that the deviation from ideal behavior is due to a combination of non‐specific and specific solvent–probe interactions. Its thermo‐solvatochromism has been studied in mixtures of water with methanol, ethanol, 1‐propanol, 2‐propanol and 2‐methyl‐2‐propanol, respectively. The data obtained were analyzed according to a recently introduced model that explicitly considers the presence of 1:1 alcohol–water hydrogen‐bonded species, ROH–W, in bulk solution, and its exchange equilibria with water and alcohol in the probe solvation microsphere. The composition of the latter is given in terms of the appropriate set of solvent fractionation factors. These indicate that the probe is more solvated by alcohol than by water. Additionally, solvation by ROH–W is favored over solvation by either W or ROH. Solvation by alcohols is more affected by probe–ROH hydrophobic interactions than by hydrogen bonding of ROH to the probe phenolate oxygen. Temperature increase results in a gradual desolvation of the probe, due to a decrease in the hydrogen bonding of all components of the binary solvent mixture. The probe has been employed to calculate the effective concentration of interfacial water of sodium dodecyl sulfate micelles, which is 38.9 mol l−1. Copyright © 2005 John Wiley & Sons, Ltd.

Dipyridamole (DIP) is known for its vasodilating and antiplatelet activity, exhibiting also a potent antioxidant effect, strongly inhibiting lipid peroxidation. This effect has been studied in mitochondria and a correlation between the DIP derivatives' structure, the ability to bind to micelles and biological activity has been suggested. In the present work, the quenching of singlet molecular oxygen, O(2)((1)Delta(g)), by DIP and RA47 and RA25 derivatives was analyzed in acetonitrile (ACN) and aqueous acid solutions. Laser flash photolysis excitation of methylene blue (MB) was made at 532 nm and monomol light emission of O(2)((1)Delta(g)) was monitored at 1270 nm. Bimolecular quenching constants in ACN are consistent with an efficient physical quenching, presenting values a bit lower than the diffusion limit (k(t) = 3.4-6.8 x 10(8) M(-1 )s(-1)). The quenching process probably occurs via reversible charge transfer with the formation of an exciplex. Calculation of DeltaG(et) associated with O(2)((1)Delta(g)) quenching corroborates with uncompleted electron transfer. In aqueous acid solutions (pH = 3.0), the k(t) values for DIP and derivatives are 20-fold smaller when compared with ACN. The electrochemical properties of DIP in ACN are characterized by two consecutive one-electron processes with half-wave oxidation potentials of 0.30 and 0.67 V vs saturated calomel electrode (SCE). However, in an aqueous acid medium, a single oxidation wave is observed involving a two-electron process (0.80 V vs SCE). Therefore, O(2)((1)Delta(g)) quenching is consistent with electrochemical data.

Background Transthyretin Cardiac amyloidosis (ATTR) presents with diffuse deposition of amyloid fibrils in the heart. Biomarkers of cardiac involvement such as troponins are often elevated even in early disease stages, reflecting direct cardiomyocyte damage and coronary microvascular dysfunction by amyloid deposits. Objectives Evaluate global and segmental coronary flow reserve (CFR) by PET 13N-ammonia in patients with hereditary Transtirretina Amyloidosis with and without cardiac involvement. Methodology Thirty-eight ATTR mutation carrier patients (18 with cardiac amyloidosis and 20 without cardiac amyloidosis underwent CFR study by PET 13N-ammonia. Cardiac involvement was defined by means of echocardiography, with an end-diastolic interventricular septal wall thickness ≥12 mm or positive endomyocardial biopsy or grade II or III nuclear scintigraphy using bone avid radiotracers. The Mann-Whitney test was used to compare the values of coronary flow reserve between the groups. The effect size was calculated using the Wilcox method and 95% confidence intervals, obtained by bootstrapping. A multivariate linear regression model was applied to identify the main determinants of global coronary flow reserve. Results Compared with patients without cardiac involvement, patients with cardiac involvement were older (69±8 vs. 41±11 years old; p<0,001), had worse NYHA functional classification, higher left ventricular mass index (198±51 g/m2 x 75±19 g/m2; p<0,001), thicker interventricular septum (17,9±3,4 mm vs. 8,7 ± mm; p<0,001]. Coronary flow reserve values were significantly lower in the cardiac amyloidosis group globally (1,8±0,4 vs. 2,9±0,7; p<0,001) and in all analyzed segments (p<0.01). The apical segments were also affected when comparing group with and without cardiac involvement (2,0±1 vs. 3,0±0,7; P=0,002), suggesting absence of microvascular apical preservation. In multivariable linear regression analyses, age and BNP were the main factors associated to coronary reserve flow. The reduction in global CRF was 0,25, 0,08 and 0,17 points, on average, for each decade of life, for each 100 mg/dl of serum BNP and for each 0,1 heart to contralateral lung ratio uptake in 3-hour caption on TcPYP scintigraphy respectively. Conclusion Patients with cardiac amyloidosis present lower coronary flow reserve both globally and segmental compared to mutation carrier without cardiac amyloidosis. The evaluation of Coronary flow reserve by PET 13N-ammonia may be a worthwhile tool in cardiac involvement in TTR patients. Funding Acknowledgement Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): Pfizer