Synthesis Single Crystal X-ray Structure DFT Studies and Hirshfeld Analysis of New Benzylsulfanyl-Triazolyl-Indole Scaffold

Benzylsulfanyl-triazolyl-indole scaffold was synthesized through coupling of 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione and benzyl bromide in EtOH under basic conditions (K2CO3). The benzylation direction was deduced from the 13C NMR signal found at 35.09 ppm, assigned for the methylene carbon of the benzyl group, this value indicates that the benzyl group attacks sulfur, not nitrogen. 1H NMR, 13C NMR, COSY, HMQC, HRMS and X-ray single crystal diffraction analysis were used for structure assignment. The desired compound accomplished in good yield. Hirshfeld analysis revealed the importance of the short N...H (1.994–2.595 Ǻ), S…H (2.282 Ǻ) and C…H (2.670 Ǻ) contacts as well as the weak π-π stacking interactions in the molecular packing of benzylthio-triazolyl-indole scaffold. Its electronic and structural aspects were predicted using density functional theory (DFT) calculations and the reactivity descriptors as well. The Uv-Vis spectral bands were assigned based on the time-dependant density functional theory TD-DFT calculations, while the gauge-including atomic orbitals (GIAO) method was used to predict the 1H and 13C NMR chemical shifts.


Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of m for many molecules with high importance in pharmaceutical field are decorated with the triazole motif. Letrozole (anti-cancer agent) and Maraviroc (Anti-HIV agent) are common drugs bearing the tr thiol and amino groups into positions 3 and 4 of 1,2,4-triazole c highly desirable, because it can provide a divergent in the molec medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], cor a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of which has been proven to be active for cancer treatment [12]. Th indole compounds has been widely explored towards many of the the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lin and MES-SA) promyelocytic leukemic cells [15], and multidrug-re

Introduction
The 1,2,4-triazole scaffold is a remarkable ring for many molecules with high importance in pharm are decorated with the triazole motif. Letrozole (an and Maraviroc (Anti-HIV agent) are common drug thiol and amino groups into positions 3 and 4 of highly desirable, because it can provide a diverge medicinal targets [6,7] such as antifungal, [8] antimi a chelating agent with metals for fluorescent applica One of the most privileged structures known which has been proven to be active for cancer tre indole compounds has been widely explored towar the MOLT-3 and HepG-2 cancer cell lines [13], breas and MES-SA) promyelocytic leukemic cells [15], an

Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of medicinal chemistry and synthon for many molecules with high importance in pharmaceutical field [1][2][3][4][5]. Many drugs on the market are decorated with the triazole motif. Letrozole (anti-cancer agent), Fluconazole (anti-fungal agent), and Maraviroc (Anti-HIV agent) are common drugs bearing the triazole motif. The introduction of thiol and amino groups into positions 3 and 4 of 1,2,4-triazole core structure make this scaffold highly desirable, because it can provide a divergent in the molecular complexity with promising medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], corrosion inhibitors [10], and also as a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of chemistry is the indole scaffold, which has been proven to be active for cancer treatment [12]. The cytotoxicity of the substituted indole compounds has been widely explored towards many of the human cancer lines, for example, the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lines (MCF-7) [14], parental (HCT15 and MES-SA) promyelocytic leukemic cells [15], and multidrug-resistant (MDR; HCT15/CL02 and

Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of medicinal chemistry and synthon for many molecules with high importance in pharmaceutical field [1][2][3][4][5]. Many drugs on the market are decorated with the triazole motif. Letrozole (anti-cancer agent), Fluconazole (anti-fungal agent), and Maraviroc (Anti-HIV agent) are common drugs bearing the triazole motif. The introduction of thiol and amino groups into positions 3 and 4 of 1,2,4-triazole core structure make this scaffold highly desirable, because it can provide a divergent in the molecular complexity with promising medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], corrosion inhibitors [10], and also as a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of chemistry is the indole scaffold, which has been proven to be active for cancer treatment [12]. The cytotoxicity of the substituted indole compounds has been widely explored towards many of the human cancer lines, for example, the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lines (MCF-7) [14], parental (HCT15 and MES-SA) promyelocytic leukemic cells [15], and multidrug-resistant (MDR; HCT15/CL02 and MES-SA/DX5) cell lines [16], and other cancer cell lines as well [17,18]. The combination of the indole moiety with variety of other privilege core structure, for example, triazoles, [19], thiazoles [20], and sulfonamides [21], leads to the enhancement of the anticancer activity [22].
Building on the findings mentioned above, and continuing in our research program [27][28][29][30][31], we have reported the synthesis of a new S-benzylated compound based on the indole and 1,2,4-triazole moieties. The new hit structure was assigned based on the nuclear magnetic resonance and X-ray diffraction analyses. Hirshfeld analysis and density functional theory (DFT) study were also explored.

General
Melting points are uncorrected and measured using a melting-point apparatus (SMP10) in open capillaries. The progress of the reaction was observed by thin layer chromatography (TLC) using ethyl acetate/n-hexane 1:1 as eluent. 1 H NMR and 13 C NMR and 2D NMR spectra were recorded using a Brucker 300 MHz spectrometer in DMSO-d 6 using TMS as internal standard. Mass spectra were recorded on JMS-600H JEOL spectrometer. λmax was measured using T90 + UV/VIS spectrometer. All software employed in this study, including X-ray diffraction analysis, Hirshfeld surface analysis, and computational methods, are described in the Supplementary Materials. Starting material 1 was synthesized in our laboratory at Suez Canal University (Ismailia, Egypt), benzyl bromide, K 2 CO 3 and ethanol were purchased from Merck (Munich, Germany).

Synthesis of the Target Compound and Structural Elucidation
4-Amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione 1 was synthesized, according to the reported procedures in [32], and reacted with benzyl bromide in the presence of K2CO3 in EtOH and stirring overnight. Coupling was explored that it proceed at sulfur to give 3-(benzylsulfanyl)-5-(1H-indol-2-yl)-4H-1,2,4-triazol-4-amine 2 (Scheme 1). The compound 2 was obtained in a pure form after recrystallization. The chemical feature of the S-benzylated compound has been assigned based on NMR and X-ray diffraction analysis. The structure of 3-(benzylsulfanyl)-5-(1H-indol-2-yl)-4H-1,2,4-triazol-4-amine was confirmed based upon its NMR and mass spectral data. 1 H NMR displayed the methylene protons of the benzyl group at 4.45 ppm, the amino group protons appeared at 6.21 ppm, the indole and phenyl CH protons appeared between 7.03 and 7.60 ppm, and the indole NH was found at 11.74 ppm. 13  Sulfur not nitrogen alkylation was confirmed from the methylene carbon signal of the benzyl group which was found in 13 C NMR at 35.09 ppm. 1 H-1 H correlation spectroscopy (COSY) was used for assigning the correlation between the vicinal protons, and 2D HMQC showed the correlation between the carbons and directly attached hydrogens (all the spectrum are provided in the Supplementary Information, Figures S1-S6)).

Structural Features of the Target Compound
The structure of 2 crystallized in monoclinic crystal system and space group C2/c with one molecule per asymmetric unit and Z = 8. The structure details and refinement parameters are listed in Table 1. Tables S1 and S2 (Supplementary data) contains the geometric parameters of 2, as obtained from the X-ray structure. The structure comprised three planar rings which are the indole (ring A), triazole (ring B) and phenyl (ring C) moieties ( Figure 1). The two rings A and B are slightly not coplanar, where the angle between the mean planes through them is only 8.2º. In contrast, the two rings B and C are strongly twisted from one another. The angle between their mean planes is 69.4º.  (3), The structure of 3-(benzylsulfanyl)-5-(1H-indol-2-yl)-4H-1,2,4-triazol-4-amine was confirmed based upon its NMR and mass spectral data. 1 H NMR displayed the methylene protons of the benzyl group at 4.45 ppm, the amino group protons appeared at 6.21 ppm, the indole and phenyl CH protons appeared between 7.03 and 7.60 ppm, and the indole NH was found at 11.74 ppm. 13

Structural Features of the Target Compound
The structure of 2 crystallized in monoclinic crystal system and space group C2/c with one molecule per asymmetric unit and Z = 8. The structure details and refinement parameters are listed in Table 1. Tables S1 and S2 (Supplementary data) contains the geometric parameters of 2, as obtained from the X-ray structure. The structure comprised three planar rings which are the indole (ring A), triazole (ring B) and phenyl (ring C) moieties ( Figure 1). The two rings A and B are slightly not coplanar, where the angle between the mean planes through them is only 8.2º. In contrast, the two rings B and C are strongly twisted from one another. The angle between their mean planes is 69.4º.  The molecular packing of 2 is controlled mainly by strong N-H…N hydrogen bonds listed in Table 2 and shown in Figure 2A. In addition, there is one N-H…π interaction between one N-H bond of the amino group and carbon atom from phenyl ring in a neighboring molecule with H…C distance of 2.389 Å. The packing of molecular units via strong N-H…N and weak N-H…π The molecular packing of 2 is controlled mainly by strong N-H...N hydrogen bonds listed in Table 2 and shown in Figure 2A. In addition, there is one N-H...π interaction between one N-H bond of the amino group and carbon atom from phenyl ring in a neighboring molecule with H...C distance of 2.389 Å. The packing of molecular units via strong N-H...N and weak N-H...π interactions is shown in Figure 2B.  The molecular packing of 2 is controlled mainly by strong N-H…N hydrogen bonds listed in Table 2 and shown in Figure 2A. In addition, there is one N-H…π interaction between one N-H bond of the amino group and carbon atom from phenyl ring in a neighboring molecule with H…C distance of 2.389 Å. The packing of molecular units via strong N-H…N and weak N-H…π interactions is shown in Figure 2B.  (3) 167 (3) N1-H1A···N2 ii 0.86 (2) 2.14 (2) 2.947 (2) 158 (2) Symmetry codes: (i) x, −y+1, z−1/2; (ii) −x+1, y, −z+3/2.

Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of medicinal chemistry an for many molecules with high importance in pharmaceutical field [1][2][3][4][5]. Many drugs on t are decorated with the triazole motif. Letrozole (anti-cancer agent), Fluconazole (anti-fung and Maraviroc (Anti-HIV agent) are common drugs bearing the triazole motif. The introd thiol and amino groups into positions 3 and 4 of 1,2,4-triazole core structure make thi highly desirable, because it can provide a divergent in the molecular complexity with p medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], corrosion inhibitors [10], a a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of chemistry is the indole which has been proven to be active for cancer treatment [12]. The cytotoxicity of the s indole compounds has been widely explored towards many of the human cancer lines, for the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lines (MCF-7) [14], parent and MES-SA) promyelocytic leukemic cells [15], and multidrug-resistant (MDR; HCT15/ Abstract: Benzylsulfanyl-triazolyl-indole scaffold was synthesi 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione and benzyl bro conditions (K2CO3). The benzylation direction was deduced from the 1 ppm, assigned for the methylene carbon of the benzyl group, this va group attacks sulfur, not nitrogen. 1 H NMR, 13 C NMR, COSY, HM crystal diffraction analysis were used for structure assignmen accomplished in good yield. Hirshfeld analysis revealed the im (1.994-2.595 Ǻ ), S…H (2.282 Ǻ) and C…H (2.670 Ǻ) contacts as w interactions in the molecular packing of benzylthio-triazolyl-indole structural aspects were predicted using density functional theory reactivity descriptors as well. The Uv-Vis spectral bands we time-dependant density functional theory TD-DFT calculations, whil orbitals (GIAO) method was used to predict the 1 H and 13 C NMR chem Keywords: triazolyl-indole; thiol; DFT; Hirshfeld surface analysis

Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of med for many molecules with high importance in pharmaceutical field [1-5 are decorated with the triazole motif. Letrozole (anti-cancer agent), Flu and Maraviroc (Anti-HIV agent) are common drugs bearing the triazo thiol and amino groups into positions 3 and 4 of 1,2,4-triazole core highly desirable, because it can provide a divergent in the molecula medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], corrosi a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of che which has been proven to be active for cancer treatment [12]. The c indole compounds has been widely explored towards many of the hum the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lines (M and MES-SA) promyelocytic leukemic cells [15], and multidrug-resist Abstract: Benzylsulfanyl-triazolyl-indole scaffold was synthesized through coup 4-amino-5-(1H-indol-2-yl)-1,2,4-triazol-3(2H)-thione and benzyl bromide in EtOH und conditions (K2CO3). The benzylation direction was deduced from the 13 C NMR signal found ppm, assigned for the methylene carbon of the benzyl group, this value indicates that the group attacks sulfur, not nitrogen. 1 H NMR, 13 C NMR, COSY, HMQC, HRMS and X-ra crystal diffraction analysis were used for structure assignment. The desired com accomplished in good yield. Hirshfeld analysis revealed the importance of the sho (1.994-2.595 Ǻ ), S…H (2.282 Ǻ) and C…H (2.670 Ǻ) contacts as well as the weak π-π interactions in the molecular packing of benzylthio-triazolyl-indole scaffold. Its electro structural aspects were predicted using density functional theory (DFT) calculations reactivity descriptors as well. The Uv-Vis spectral bands were assigned based time-dependant density functional theory TD-DFT calculations, while the gauge-including orbitals (GIAO) method was used to predict the 1 H and 13 C NMR chemical shifts.

Introduction
The 1,2,4-triazole scaffold is a remarkable ring in the field of medicinal chemistry and for many molecules with high importance in pharmaceutical field [1][2][3][4][5]. Many drugs on the are decorated with the triazole motif. Letrozole (anti-cancer agent), Fluconazole (anti-funga and Maraviroc (Anti-HIV agent) are common drugs bearing the triazole motif. The introdu thiol and amino groups into positions 3 and 4 of 1,2,4-triazole core structure make this highly desirable, because it can provide a divergent in the molecular complexity with pr medicinal targets [6,7] such as antifungal, [8] antimicrobial, [9], corrosion inhibitors [10], and a chelating agent with metals for fluorescent applications [11].
One of the most privileged structures known in the field of chemistry is the indole which has been proven to be active for cancer treatment [12]. The cytotoxicity of the sub indole compounds has been widely explored towards many of the human cancer lines, for e the MOLT-3 and HepG-2 cancer cell lines [13], breast cancer cell lines (MCF-7) [14], parental and MES-SA) promyelocytic leukemic cells [15], and multidrug-resistant (MDR; HCT15/C

Hirshfeld Analysis of Molecular Packing
Hirshfeld topology calculations are important to analyze the different intermolecular contacts in the structure of crystalline materials. Additionally, it sheds the light on the significance, strength and percentage of each intermolecular contact. The percentages of different contacts observed in the crystal structure of 2 based on Hirshfeld calculations are shown in Figure 3, while the complete Hirshfeld surfaces are given in Figure S7    The presence of some C...C (6.1%) and C...N (4.6%) contacts, as well as the blue/red triangles in the shape index Hirshfeld surface ( Figure 5), are the main characteristics for the presence of π-π stacking interactions. The shortest C...C and C...N interaction distances are presented in Table 3. Generally, all these contacts are slightly longer than the van der Waals radii sum of the interacting elements, indicating weak π-π contacts. Table 3. Contact distances of the most significant π-π interactions.

Contact
Distance ( Crystals 2020, 10, x FOR PEER REVIEW 7 of 14  DFT studies: the optimized geometry of 2 is presented in Figure 6. Structure matching between the computed molecular geometry with the experimental one is also presented. This structure comparison indicated very well the good agreement between the optimized and X-ray structures. In addition, the very good straight-line relations between the calculated and experimental geometric parameters further confirm this conclusion. The values of correlation coefficients are very close to 1 for both cases (Figure 7). A complete set of bond distances and angles are given in  The presence of some C…C (6.1%) and C…N (4.6%) contacts, as well as the blue/red triangles in the shape index Hirshfeld surface ( Figure 5), are the main characteristics for the presence of π-π stacking interactions. The shortest C…C and C…N interaction distances are presented in Table 3. Generally, all these contacts are slightly longer than the van der Waals radii sum of the interacting elements, indicating weak π-π contacts. DFT studies: the optimized geometry of 2 is presented in Figure 6. Structure matching between the computed molecular geometry with the experimental one is also presented. This structure comparison indicated very well the good agreement between the optimized and X-ray structures. In addition, the very good straight-line relations between the calculated and experimental geometric parameters further confirm this conclusion. The values of correlation coefficients are very close to 1 for both cases (Figure 7). A complete set of bond distances and angles are given in Table S3 (Supplementary Data).  DFT studies: the optimized geometry of 2 is presented in Figure 6. Structure matching between the computed molecular geometry with the experimental one is also presented. This structure comparison indicated very well the good agreement between the optimized and X-ray structures. In addition, the very good straight-line relations between the calculated and experimental geometric parameters further confirm this conclusion. The values of correlation coefficients are very close to 1 for both cases (Figure 7). A complete set of bond distances and angles are given in Table S3 (Supplementary Data).    DFT studies: the optimized geometry of 2 is presented in Figure 6. Structure matching between the computed molecular geometry with the experimental one is also presented. This structure comparison indicated very well the good agreement between the optimized and X-ray structures. In addition, the very good straight-line relations between the calculated and experimental geometric parameters further confirm this conclusion. The values of correlation coefficients are very close to 1 for both cases (Figure 7). A complete set of bond distances and angles are given in Table S3 (Supplementary Data). The natural charges obtained from the NBO calculations are listed in Table 4. All hydrogen atoms are electropositive with the highest partial charges located at the NH protons. Additionally, the sulphur atom has partial positive charge of 0.3054 e. In contrast, all nitrogen atoms have negative partial charges. The maximum negative charge is located over the amine nitrogen atom.  The natural charges obtained from the NBO calculations are listed in Table 4. All hydrogen atoms are electropositive with the highest partial charges located at the NH protons. Additionally, the sulphur atom has partial positive charge of 0.3054 e. In contrast, all nitrogen atoms have negative partial charges. The maximum negative charge is located over the amine nitrogen atom. Additionally, all carbon atoms have negative partial charges except those attached directly to the electronegative nitrogen sites. As a result of this charge distribution, the compound is predicted to be polar molecule with calculated dipole moment of 2.2557 Debye. Molecular electrostatic potential (MESP), along with the dipole vector are presented Figure 8.  The natural charges obtained from the NBO calculations are listed in Table 4. All hydrogen atoms are electropositive with the highest partial charges located at the NH protons. Additionally, the sulphur atom has partial positive charge of 0.3054 e. In contrast, all nitrogen atoms have negative partial charges. The maximum negative charge is located over the amine nitrogen atom. Additionally, all carbon atoms have negative partial charges except those attached directly to the electronegative nitrogen sites. As a result of this charge distribution, the compound is predicted to be polar molecule with calculated dipole moment of 2.2557 Debye. Molecular electrostatic potential (MESP), along with the dipole vector are presented Figure 8.  Figure 6. In addition, the HOMO and LUMO are important for the molecule reactivity [33][34][35][36][37][38][39]. Their energies were calculated to be −5.454 and −1.070 eV, respectively. The energies of these molecular orbitals were used to calculate the reactivity descriptors using Equations (1)- (5).
Crystals 2020, 10, 685 9 of 14 Hence, the calculated ionization potential (I) and electron affinity (A) are 5.454 and 1.070 eV, respectively. Additionally, the hardness (η), electrophilicity index (ω) and chemical potential (µ) are 4.384, 1.213 and −3.262 eV, respectively. The HOMO is located over the sulphur atom and the triazole π-system. These sites represent the ground state demand for electronic transition to the higher energy level (LUMO). The latter is distributed over the triazole and indole moieties. Hence, the HOMO to LUMO excitation represent mixed n-π* and π-π* transitions. The energy needed for this intermolecular charge transfer is 4.384 eV.
UV-Vis and NMR spectra: The experimental UV-Vis electronic spectra of 2 in ethanol showed absorption bands at 244 and 307 nm, and a shoulder at 295 nm. The assignments of these electronic transitions are presented in Table 5 based on the TD-DFT calculations. The experimental and simulated electronic spectra are shown in Figure 9. The experimentally observed bands were calculated at 232.3 nm (f = 0.248), 305.5 nm (f = 1.020) and 288.8 nm (f = 0.069), respectively, which correspond to HOMO→L+3 (81%), HOMO→LUMO (96%) and H-1→LUMO (92%) transitions, respectively. Presentation of the molecular orbitals involved in these electronic transitions is shown in Figure 10.
Hence, the calculated ionization potential (I) and electron affinity (A) are 5.454 and 1.070 eV, respectively. Additionally, the hardness (η), electrophilicity index (ω) and chemical potential (μ) are 4.384, 1.213 and −3.262 eV, respectively. The HOMO is located over the sulphur atom and the triazole π-system. These sites represent the ground state demand for electronic transition to the higher energy level (LUMO). The latter is distributed over the triazole and indole moieties. Hence, the HOMO to LUMO excitation represent mixed n-π* and π-π* transitions. The energy needed for this intermolecular charge transfer is 4.384 eV.
UV-Vis and NMR spectra: The experimental UV-Vis electronic spectra of 2 in ethanol showed absorption bands at 244 and 307 nm, and a shoulder at 295 nm. The assignments of these electronic transitions are presented in Table 5 based on the TD-DFT calculations. The experimental and simulated electronic spectra are shown in Figure 9. The experimentally observed bands were calculated at 232.3 nm (f = 0.248), 305.5 nm (f = 1.020) and 288.8 nm (f = 0.069), respectively, which correspond to HOMO→L+3 (81%), HOMO→LUMO (96%) and H-1→LUMO (92%) transitions, respectively. Presentation of the molecular orbitals involved in these electronic transitions is shown in Figure 10.    In addition, the geometry optimization is performed in DMSO as solvent, then the NMR chemical shifts are calculated in the same solvent using TMS as internal standard. The results are summarized in Table S4 (Supplementary Data), in comparison with the experimental data. Moreover, graphical plots of the experimental chemical shifts against the calculated data for protons and carbons are presented in Figure 11. As can be seen from this figure, the straight lines have good correlation coefficients, indicating the good agreement between the calculated and experimental results. In addition, the geometry optimization is performed in DMSO as solvent, then the NMR chemical shifts are calculated in the same solvent using TMS as internal standard. The results are summarized in Table S4 (Supplementary Data), in comparison with the experimental data. Moreover, graphical plots of the experimental chemical shifts against the calculated data for protons and carbons are presented in Figure 11. As can be seen from this figure, the straight lines have good correlation coefficients, indicating the good agreement between the calculated and experimental results. NBO analysis: the electron delocalization processes from occupied orbitals to antibonding empty orbitals stabilized the system, due to the conjugation effect [40,41]. The stabilization energies (E (2) ) of these electron delocalization processes in 2 are listed in Table 6. The molecule is stabilized by many σ-σ*, π→π*, n→σ* and n→π* IMCT interactions. The σ-σ* and n→σ* IMCT interactions are generally weak, with maximum stabilization of 6.79 and 9.95 kcal/mol for σ(C19-C20)→ σ*C22-C23 and n(N9)→σ*(N8-C23) IMCT interactions, respectively. In contrast, the π→π*, and n→π* are generally stronger, which stabilized the system up to 20.67 and 45.73 kcal/mol for π(C31-C33)→ π*(C28-C29) and n(N8)→ π *(N7-C24) IMCT interactions, respectively. Donor NBO Acceptor NBO E (2) Donor NBO Acceptor NBO E (2) σ→σ* n→σ* Figure 11. Correlation graphs between the calculated and experimental 1 H (a) and 13 C (b) NMR chemical shifts.
Supplementary Materials: The following are available online at http://www.mdpi.com/2073-4352/10/8/685/s1. Figure S1: 1 H NMR of the target compound; Figure S2: 13 C NMR of the target compound; Figure S3: D-COSY of the target compound; Figure S4: DEPT-135 of the target compound; Figure S5: DEPT-90 of the target compound; Figure S6: 2D-HMQC of the target compound; Figure S7: LRMS (EI) of the target compound; Figure S8: Hirshfeld surfaces of 2; Table S1: Bond lengths for 2; Table S2: Bond angles for 2; Table S3: The calculated geometric parameters of the studied compound a ; Table S4: The calculated and experimental chemical shifts (ppm) for the studied compound a .