Solvatochromic and theoretical study of 1,3-benzodioxole derivative

The solvatochromic UV-Vis absorption and emission characteristics of (E)-1-(4-hydroxypiperidin-1-yl)-3-(7-methoxybenzo[d][1,3]dioxol-5-yl)prop-2-en-1-one compound were studied in solvents of various polarities. The various types of interactions present between the solute-solvent were studied by means of Catalan’s and Kamlet’s techniques. Furthermore, the excited state dipole moment of the compound was estimated using the Lippert’s, Kawski-Chamma-Viallet’s, Bakhshiev’s, and ENT solvent polarity parameters. It was noticed that the excited state dipole moment was more than the dipole moment in the ground state. Investigated further to comprehend the compound’s molecular properties through theoretical study.


Introduction
Heterocyclic molecules have a significant and productive role in the discovery of drugs because of their broad range of bioactivity.The heterocyclic molecules with the benzodioxole structural motif hold an important place in both natural and synthetic organic chemistry.Benzodioxole is an essential component of many natural products, like piperine and sesamol.Specifically, 1,3benzodioxole derivatives are found in a wide range of compounds with significant biological and therapeutic applications, such as antimicrobial, antitumor, anti-JH and COX-2 inhibitor [1][2][3][4].LASSBio-294, a novel bioactive compound of 1,3-benzodioxole class, shown vasodilatory and inotropic effects [5].1,3-Benzodioxole derivatives have been shown to show cytotoxic activity against several human tumour cell lines, for instance, multidrug-resistant nasopharyngeal carcinoma cells [6] and human colon carcinoma cells [7].Compounds with piperidin derivatives are well known drugs like alfentanil, fentanyl, sufentanil, thenaldine, pimozide, domperidone, astemizol, indoramin, diphenylpyraline, loperamide etc. Piperidine derivatives have a wide-ranging of biological activities, like, antiviral, antifungal, analgesic, antibacterial, and hypotensive [8][9][10].Solvatochromism studies are of common interest among experts due to their possible applications in optical light-emitting diodes, solvent polarity determination, explosives finding using colorimetric chemosensors, dye-sensitized solar cells, photoluminescent materials, and volatile organic materials for laser applications [11][12][13].Not only is the solvatochromic method a straightforward procedure, but it is also reasonably priced.Since the excited state can be better understood by looking at the solvent-dependent absorption and emission properties, the solvatochromic method is employed to understand the nonlinear optical properties, which are primarily expressions of an organic molecule's excited state (ES) nature.Along with the solvatochromic approach, theoretical calculations have evolved into an a priori tool for calculating the NLO of organic materials during the last few decades.Density functional theory (DFT) based methods are beneficial in having a prior understanding of the properties and the factors leading the effectiveness of NLOs.[14][15][16][17].
The compound chosen in the current study is was explored in the current study by means of solvent polarity variables and multiple linear regression studies.Solvatochromic shifts were utilised in evaluation of the ES dipole moment, while DFT calculations were employed in evaluation of ground-state (GS) dipole moment.
Several physicochemical properties, optimised molecular structure and HOMO-LUMO energies were calculated and analysed at the BLYP levels of theory.

Materials
HPLC grade solvents were used in the present work, that is toluene, tetrahydrofuran (THF), ethyl acetate (EAC), acetone, dimethyl sulfoxide (DMSO), acetonitrile (ACN), butanol, propanol, ethanol, methanol, and E47MBD1 compound was procured from commercial dealers.The structure of the E47MBD1 is given in Fig. 1

Experimental Methods
A Shimadzu spectrophotometer was employed to record the absorption spectra.A JASCO spectrofluorometer was utilized to record the emission spectra.Experimental results were accomplished at a small concentration of compound (0.05 nM) to minimize aggregation development and self-absorption.

Solvents' effects on photophysical characteristics
When it pertains to alcohols, there is a slight variance in the absorption peak of E47MBD1.
But fluorescence spectra maxima in alcohols differ to some extent from those of non-alcohols, indicating a distinct solvent -solute interaction.This implies that variations in the polarity of the solvent and the features of H2 bonds have no effect on the distribution of energy in GS of the E47MBD1.Conversely, Variations in the solvent's polarity have a direct impact on the distribution of energy in ES.AS and NAS showed a surge in Stokes' shift, which rises with increasing solvent polarity.There could be specific solute-solvent interactions causing this.The redshift results from an effective intermolecular interface with the ES of the polar solvents caused by a significant distinction between the solute's ES and the spreading of GS charge [31].
Alcohols follow a specific trend, in contrast to non-alcohols.
To explore the solvatochromic nature of E47MBD1 more, spectroscopic properties (Ȟf and ǻȞ) are related with apt polarity variables of solvent.The graphs Ȟf and ǻȞ verses ǻf (İ,n) are plotted and the least-square correlation gives a modest correlation Ȟf (0.73) and ǻȞ (0.58) for E47MBD1.Plots are reported in Fig. 4. The above correlation elucidate that the ǻf(İ,n) is a not suitable polarity measure in this study.
The low correlation observed above may be due in part to the approach's lack of solute-solvent interactions.It is thought that the correlation is strengthened by molecular features of solvation, H2 bond interactions, charge transfer relations and complex formation.Hereafter, the Ȟf and ǻȞ are explained by the ‫ܧ‬ ே ் parameter, were taken from the works [27].The Ȟf and ǻȞ are associated with ‫ܧ‬ ே ் and are reported in Fig. 5.The least-square correlation study providing a decent correlation for both Ȟf (0.92) and ǻȞ (0.91).But, when Ȟf and ǻȞ were associated with ‫ܧ‬ ே ் distinctly for NAS and AS.A decent correlation was detected and graphs are reported in Fig. 6.In the case of alcohols, correlation of Ȟf and ǻ Ȟ were obtained to be 0.99 and 0.68, respectively.The correlation for Ȟf and ǻȞ was observed to be 0.94 for NAS.The solvent stabilization of GS and ESs persuades solvent-solute interactions, as revealed by a double linear fit.Particularly, these interactions comprise of dipole-dipole interactions and H2 bonding [32].As protic solvent polarity rises, hydrogen bonding stabilises the compound.However, dipole-dipole and induced dipole effects are thought to be the primary sources of interactions in proton donor solvents [33].From the Equation (C) and (D), When compared to the Kamlet approach, the correlation is thought to be reasonably good.The polarizability and dipolarity of the solvent are shown by these relations.However, observed that the SA's effect was greater than the SB's in both the Catalan and Kamlet models.The theoretically projected dipole moment of GS (ȝg) of the E47MBD1 was reported in Table 4.The graphs of (Ȟa-Ȟf) with F1, and (Ȟa +Ȟf)/2 with F2 are reported in Fig. 7.

Optimized molecular geometry
Theoretical calculation is a powerful instrument to explore the relationship between the structure, site selectivity and chemical reactivity of many biomolecules and also offers a theoretical support for the new approachs of synthesis of compounds for biomedical applications.Computed frontier molecular orbital's energy and global reactivity descriptors are dynamic features in the growth of novel drugs and explains the chemical's reactivity.The optimization of E47MBD1 was accomplished using 6-31G/B3LYP.E47MBD1.Optimized structure with nonappearance of imaginary frequencies suggests the accomplishment of minimum energy and is reported in Fig. 9 with labels.Also, DFT calculations admit that the E47MBD1 fits to C1 point symmetry [35].

3.. Frontier molecular orbital (FMO) study
FMOs analysis was used to look into a molecule's stability [36].The FMOs calculated for E47MBD1 by means of DFT are reported in Fig. 10.[1,3]dioxol-5-yl)but-3-en-2-one part of the compound.EHOMO -ELUMO gap (Eg) is well known to be relative to the reaction stability of molecule [36,37].Electron transitions are enhanced when the Eg is smaller, suggesting a decrease in the compounds' reaction stability [38,39].The Eg count on the intermolecular charge transfer (ICT) ability of the electron acceptors and donors.The FMOs results of E47MBD1 is reported in Table 5.The computed Eg of the E47MBD1 was found to be 4.0602 eV.

3.. Global reactivity descriptors
In addition to the FMOs, reactivity descriptors for example the electron affinity (EA), the ionization potential (IP) [40], softness (S), hardness (Ș and partial molar Gibbs energy (ȝ (Table 5).Chemically, molecules with a higher IP and a lower EA are less reactive than those with a lower IP and a higher EA.The hardness (Ș is reciprocal proportion to softness (S) and are vital in defining the transfer of charge confrontation [41].A molecule exhibits greater chemical stability when its hardness value is higher.Similarly, ȝ reveals the propensity of losing electrons.The negative value for ȝ implies the stability of E47MBD1, proves the substance doesn't break down into its constituent elements [42].

Conclusion
The absorption and emission characteristics of the biologically active E47MBD1 was analysed in solvents of different polarities.The various types of interactions present between the solutesolvent were analysed using Catalan's and Kamlet's multiple linear regression techniques.Both hydrogen bonding and universal solute-solvent interactions are present in the system.However, hydrogen bonding interactions are less significant than typical solute-solvent interactions.
DFT studies were performed through the Gaussian 09 software [28].Computations were completed at B3LYP levels of theory with basis sets 6-31G.Gauss View was utilised to visualise the outcomes [29].

Fig. 2
Fig. 2 and 3 show the absorption and emission spectra of E47MBD1 in the chosen solvents.

Fig. 6 :
Fig. 6: ǻȞ and Ȟf versus ‫ܧ‬ ே ் for E47MBD1 separately for NAS and AS.To realize the effect of the H2 bond acceptor (HBA) and H2 bond donor (HBD) of solvent on the Ȟf and ǻȞ, ǻȞ and Ȟf are associated with Į ȕ and ʌ by means of the by Kamlet's method.The values of Į ȕ and ʌ* are noted from the works[34,35].The results are presented in Equations (A) and (B).

Fig. 8 :
Fig. 8: ((Ȟa + Ȟf))/2 verses F2 and ǻȞ verses F1 for E47MBD1 separately for NAS and AS.The ȝe of the E47MBD1 was also calculated by Equations (S1) and (S2).The substantial difference between ȝe and ȝg under this assumption and corresponding ȝe and ȝg from other methods proposes that ȝg and ȝe are not parallel.The angle (ࢥ) among ȝe, and ȝg predicted by means of Equation (S3) and was greater than 0. Further, the calculation of ȝe, separately for NAS and AS was done by means of the double linear fits of (Ȟa -Ȟf) with ‫ܧ‬ ே ் values.Estimated ȝe is slightly different in different methods due to the variance in assumptions.The findings suggest that the ȝe is greater than the ȝg, which shows that possibility of a highly relaxed ES.

Fig. 10 :
Fig. 10: The FMO of the E47MBD1 The majority of the HOMO of the E47MBD1 was present on the (E)-4-(7methoxybenzo[d][1,3]dioxol-5-yl)but-3-en-2-one part of the E47MBD1 and similarly, the Conference on Advanced Materials and Fluid Mechanics Journal of Physics: Conference Series .
S. No. Solvents

Table 3 :
Table 3 presents the slopes, correlation coefficients and intercepts associated with dipole moment computations.Positive slopes suggest that spectroscopic property values rise as polarity functions rise, while negative slopes suggest that spectroscopic property values fall as polarity functions rise.Data of Statistical treatment of the E47MBD1.