Spectroscopic and theoretical studies of fluorescence effects induced by the ESIPT process in a new derivative 2-Hydroxy-N-(2-phenylethyl)benzamide - Study on the effects of pH and medium polarity changes.

The paper presents the results of studies conducted with the use of stationary and time-resolved fluorescence spectroscopy for the new derivative 2-Hydroxy-N-(2-phenylethyl)benzamide (SAL-3) in aqueous solutions with various concentrations of hydrogen ions as well as in solvent mixtures (i.e. media with changing polarity/polarizability). For the compound selected for the study placed in aqueous solutions with varying concentrations of hydrogen ions, the fluorescence emission spectra revealed a single emission band within most of the pH range, however, at low pH (pH<3) a significant broadening (noticeable effect of dual fluorescence) and shifting of the band was observed. Whereas, for water and polar (protic) solvents, we observed a very interesting phenomenon of dual fluorescence never before reported for this particular group of analogues (with the specific substituent system). Based on the results of the experiments, it was observed that the presented effects may be related both with conformational effects (related to the possible positioning of the-OH group on the side of the carbonyl system, which facilitates the possibility of proton transfer) as well as, most importantly, the effects of excited state intramolecular proton transfer (ESIPT-Excited State Intramolecular Proton Transfer) related in this case with the necessary (new/previously unobserved in published literature) presence of ionic and non-ionic forms of the compound). Both the conducted quantum-mechanical [TD]DFT-Time-Dependent Density Functional Theory) calculations and excited state dipole moment change calculations for the analyzed molecule in solvents with varying pH confirmed the association between the observed fluorescence phenomena and the two aforementioned effects

<i>Lupinus angustifolius</i> seed sculpture in the mutant lines PL-41H (A, A′), PL-44H (B, B′), PL-53H (C, C′), PL-‘Emir’ (D, D′), PL-‘Sonet’ (E, E′).

<p>SEM images of seed surface (A′, B′, C′, D′, E′ – general view of seeds in inserts) and cross-section of the seed coat (A, B, C, D, E). C – cuticle; MS – macrosclereids layer; OS – osteosclereids layer; PA – parenchymal cells.</p

Mean squares from variance analysis for 1000-seed weight and seed coat percentage.

<p>*significance at the level of α = 0.05.</p><p>**significance at the level of α = 0.01.</p

The linear regression between weight of 1000 seeds and seed coat for analysed genotypes <i>Lupinus angustifolius</i>.

<p>The linear regression between weight of 1000 seeds and seed coat for analysed genotypes <i>Lupinus angustifolius</i>.</p

Nucleotide sequence and annealing temperatures of primers generating polymorphic ISSR products in the analysed genotypes.

<p>*R purine, Y pyrimidine; N any nucleotide; B indicates C, G or T; D as A, G, or T; H as A, C, or T; and V as A, C, or G.</p

Weight of 1000 seed and seed coat percentage in analysed genotypes of <i>Lupinus angustifolius</i> L.

<p>Means for each year based of three replications ± standard errors.</p><p>A,B,C …-uniform groups based on the Duncan test.</p><p>AU-originated from Australia.</p><p>PL-originated from Poland.</p><p>BY - originated from Belarus.</p><p>SEM – standard error of the means.</p

Genetic identity (Is - below the diagram) and genetic distance (Ds - above the diagonal) statistics for the analysed genotypes of <i>L. angustifolius</i>.

<p>Genetic identity (Is - below the diagram) and genetic distance (Ds - above the diagonal) statistics for the analysed genotypes of <i>L. angustifolius</i>.</p

Products of PCR-ISSR amplification after using of UBC 815 for analysed genotypes <i>Lupinus angustifolius</i>: 1 – AU-11257-19/1, 2 – PL-Sonet, 3 – PL-53H, 4 – AU-Walup, 5 – PL-44H, 6 – AU-Yorrel, 7 – PL-41H, 8 – PL-Zeus, 9 – BY-LAG24, 10 – PL-Emir.

<p>Products of PCR-ISSR amplification after using of UBC 815 for analysed genotypes <i>Lupinus angustifolius</i>: 1 – AU-11257-19/1, 2 – PL-Sonet, 3 – PL-53H, 4 – AU-Walup, 5 – PL-44H, 6 – AU-Yorrel, 7 – PL-41H, 8 – PL-Zeus, 9 – BY-LAG24, 10 – PL-Emir.</p

<i>Lupinus angustifolius</i> seed sculpture in PL-Zeus (A, A′), BY-LAG24 (B, B′), AU-11267-19 (C, C′), AU-Walup (D, D′), AU-Yorrel (E, E′).

<p>SEM images of the seed surface (A′, B′, C′, D′ E′, – general view of seeds in inserts) and cross-section of the seed coat (A, B, C, D, E). C – cuticle; MS – macrosclereids layer; OS – osteosclereids layer; PA – parenchymal cells.</p