NMR Chemical Shifts Research Articles

Elucidating the Electronic Nature of Rh-based Paddlewheel Catalysts from 103 Rh NMR Chemical Shifts: Insights from Quantum Mechanical Calculations.

The tremendous importance of dirhodium paddlewheel complexes for asymmetric catalysis is largely the result of an empirical optimization of the chiral ligand sphere about the bimetallic core. It was only recently that a H(C)Rh triple resonance 103 Rh NMR experiment provided the long-awaited opportunity to examine - with previously inconceivable accuracy - how variation of the ligands impacts on the electronic structure of such catalysts. The recorded effects are dramatic: formal replacement of only one out of eight O-atoms surrounding the metal centers in a dirhodium tetracarboxylate by an N-atom results in a shielding of the corresponding Rh-site of no less than 1000 ppm. The current paper provides the theoretical framework that allows this and related experimental observations made with a set of 19 representative rhodium complexes to be interpreted. In line with symmetry considerations, it is shown that the shielding tensor responds only to the donor ability of the equatorial ligands along the perpendicular principal axis. Axial ligands, in contrast, have no direct effect on shielding but may come into play via the electronic -effect that they exert onto the neighboring equatorial sites. On top of these fundamental interactions, charge redistribution within the core as well as the electronic -effect of ligands of different donor strengths is reflected in the recorded 103 Rh NMR shifts.

Synthesis, Structural, and Quantum Chemical Analysis of Neutral and Cationic Ruthenium(II) Complexes with Nicotinate-Polyethylene Glycol Ester Ligands

Ruthenium(II/III)-based compounds have gained significant interest due to the biocompatibility of ruthenium, its similarity to iron, and the possibility for structural diversification through the choice of ligands. In this contribution, two novel ligands, (2-(2-methoxyethoxy)ethyl nicotinate hydrochloride) and (2-[2-(2-methoxyethoxy)ethoxy]ethyl nicotinate hydrochloride) (pyCOO(CH2CH2O)nCH3: L2, n = 2; L3, n = 3), were synthesized and characterized via ESI-HRMS, as well as IR and NMR spectroscopies. Their structures were optimized at the B3LYP/6-311++G(d,p) level of theory, and NMR chemical shifts were predicted, along with the most important intramolecular interactions. Additionally, two neutral complexes of the general formula [RuCl2(η6-p-cym) (L-κN)] (L = L2: 2; L3: 3) and two cationic complexes of the general formula [RuCl(η6-p-cym)(L-κN)2][PF6] (L = L1: 4; L2: 5) were obtained and characterized. The optimization of the structures was performed at the B3LYP/6-31+G(d,p)(H,C,N,O,Cl)/LanL2DZ(Ru) level of theory. Structural features were described, and intramolecular stabilization interactions were outlined.

NMR shift prediction from small data quantities

Prediction of chemical shift in NMR using machine learning methods is typically done with the maximum amount of data available to achieve the best results. In some cases, such large amounts of data are not available, e.g. for heteronuclei. We demonstrate a novel machine learning model that is able to achieve better results than other models for relevant datasets with comparatively low amounts of data. We show this by predicting ^{19}F and ^{13}C NMR chemical shifts of small molecules in specific solvents.Graphical

Prediction of Reaction Performance by Machine Learning Using Streamlined Features: NMR Chemical Shifts as Familiar Descriptors

AbstractMachine learning (ML) has quickly emerged in synthetic organic chemistry to predict reaction outcomes such as yields and stereoselectivities. Notably, recent applications of the ML approach showed powerful performance in solving various chemical problems. However, the requirement of numerous descriptors and large datasets hampers the general use by non‐specialists. In this study, simple ML models were developed by utilizing easily available 13C‐NMR chemical shifts of the substrates as familiar descriptors to predict the site‐selectivity of geminal chlorofluorination of unsymmetrical 1,2‐dicarbonyl compounds. We identified that the feed‐forward neural network (FNN) model provides higher accuracy compared to other algorithms. Then, better prediction performance was acquired through streamlined models using minimal, only empirically relevant descriptors.

NMR characterization of novel interactions between p97 AAA+ ATPase and the p47 adaptor revealing insights into substrate delivery mechanism

p97/VCP is an essential AAA+ ATPase involved in diverse cellular activities by interacting with an array of protein adaptors that recruit p97 for specific tasks. p47 is one of the adaptors that targets p97 for membrane remodeling by forming a stable complex with p97 through multivalent interactions. Here, we report a pair of previously unidentified interactions between the N-terminal part of p47 (residues 1–94) and the N-terminal domain (NTD) of p97. Using nuclear magnetic resonance (NMR) spectroscopy, we identify two binding sites on p47, one located on the ubiquitin-associated (UBA) domain and the other on the intrinsically disordered linker, that interact with the same basic patch on p97 NTD, driven by electrostatic forces. Reciprocal NMR titration experiments between p47 (residues 1–94) and p97 NTD reveal that these interactions are relatively weak in nature with dissociation constants on the order of hundreds of micromolar to millimolar in trans. Structural models of the two interactions are developed based on NMR chemical shift perturbations, which reveal details of the tentative binding interfaces. Our findings provide new insights into the mechanism by which ubiquitinated substrates are delivered from p47 to p97 for unfolding.

Microstructural Insights into Ethylene Glycol‐Mediated Polyether Polyols Using Double Metal Cyanide Catalyst

AbstractPolyether polyols are well established category of polymers, which are synthesized via ring opening polymerization (ROP) industrially using Double Metal Cyanide (DMC) catalyst with glycols as initiators. Establishing the role of glycol in initiation and its involvement in the polymer chain during the ROP of propylene oxide (PO) via DMC catalysis is of utmost importance. In this work, the experimental method is established to understand the role of ethylene glycol (EG) and its participation during initiation and chain propagation. Furthermore, the microstructure analysis of synthesized polyether polyols reveals that ethylene glycol initiates from both sides and participated in random copolymerization besides its role as an initiator in the polymeric backbone during the ROP of PO. Also, in‐depth studies of the polymeric microstructural distribution are carried out using 1H‐1H COSY, 1H‐13C HMQC, and 1H‐13C HMBC with the aid of multi‐pulse 2D correlation techniques along with carbon‐13 NMR chemical shifts. In‐depth understanding of the microstructure of the polyether polyols is established with the aid of the obtained polymeric regio‐irregular structures. The reactivity ratios of PO are found to be 0.89 and 0.57 by modified Kelen–Tudos and Fineman–Ross method, respectively, indicating higher reactivity of PO monomer in comparison to EG.

Cobalt-59 NMR relaxation times of symmetric tris(γ-substituted-acetylacetonato)cobalt(III) complexes in benzene

Cobalt-59 NMR relaxation times, T1(59Co), and chemical shifts, δ(59Co), of symmetric tris(γ-substituted-acetylacetonato)cobalt(III) complexes, [Co(acac-X)3], which have chloride, bromide, nitro, and phenyl groups at the methine carbon atoms in the chelate ligands, have been measured in benzene at four temperatures between 284 and 319 K. In view of the viscosity dependence of 1/T1(59Co), the 59Co relaxation is caused by the reorientation of the static electric field gradient at the nucleus in every complex. Assuming that the rotational volume is replaced by the van der Waals volume, the nuclear quadrupolar coupling products, {(1 + ηq2/3)(eQq/h)2}1/2, were obtained for the series of [Co(acac-X)3] complexes in benzene. The negative correlation between {(1 + ηq2/3)(eQq/h)2}1/2 and δ(59Co) was observed for the four complexes [Co(acac)3], [Co(acac-Cl)3], [Co(acac-Br)3], and [Co(acac-NO2)3] except for [Co(acac-Ph)3]. This discrepancy strongly suggests that the rotational volume of the propeller-like [Co(acac-Ph)3] complex with the protruding phenyl groups cannot be simply treated as the van der Waals volume, different from the other almost spherical complexes. Actually, the estimation of the rotational volumes from the distances between the central cobalt and g-substituents gave much better correlation between {(1 + ηq2/3)(eQq/h)2}1/2 and δ(59Co) for all the complexes including [Co(acac-Ph)3].

Mitochondrial Acyl Carrier Protein of Leishmania major Displays Features Distinct from the Canonical Type II ACP.

Prokaryotes synthesize fatty acids using a type II synthesis pathway (FAS). In this process, the central player, i.e., the acyl carrier protein (ACP), sequesters the growing acyl chain in its internal hydrophobic cavity. As the acyl chain length increases, the cavity expands in size, which is reflected in the NMR chemical shift perturbations and crystal structures of the acyl-ACP intermediates. A few eukaryotic organelles, such as plastids and mitochondria, also harbor type II fatty acid synthesis machinery. Plastid FAS from spinach and Plasmodium falciparum has been characterized at the molecular level, but the mitochondrial pathway remains unexplored. Here, we report NMR studies of the mitochondrial acyl-acyl carrier protein intermediates of Leishmania major (acyl-LmACP). Our studies show that LmACP experiences remarkably small conformational changes upon acylation, with perturbations confined to helices II and III only. CastP determined that the cavity size of apo-LmACP (PDB entry 5ZWT) is less than that of Escherichia coli ACP (PDB 1T8K). Thus, the small chemical shift perturbations observed in the LmACP intermediates, coupled with CastP results, suggest an unusually small cavity when fully expanded. The faster rate of C8-LmACP chain hydrolysis compared to E. coli ACP (EcACP) also supports these convictions. Structure comparison of LmACP with other type II ACP disclosed unique differences in the helix I and loop I conformations, as well as several residues present there. Numerous hydrophobic residues in helix I and loop I (conserved in all mitochondrial ACPs) are substituted with hydrophilic residues in the bacterial/plastid type II ACP. For instance, Phe and leucine at positions 14 and 34 in LmACP are substituted with a hydrophilic residue and Ala in bacterial/plastid type II ACP. Mutation of Leu 34 to Ala (corresponding residue in EcACP) resulted in a complete loss of structure, underscoring its importance in maintaining the ACP fold. Thus, our NMR studies, combined with insights from the crystal structure, highlight several unique features of LmACP, distinct from the prokaryote and plastid type II ACP. Given the high sequence identity, the features might be conserved in all mitochondrial ACPs.

Monohalogenated methyl- and methoxy-benzoic acids: A combined experimental and quantum chemical theoretical study on their structure, vibrational analysis and molecular parameters

In this paper, the molecules 3-fluoro-2-methylbenzoic acid; 3-chloro-2-methoxybenzoic acid; and 3-bromo-2-methylbenzoic were investigated using experimental and quantum chemical theoretical approach for vibrational and electronic properties from the optimized structure. Becke three parameter Lee–Yang–Parr density functionals along with 6-311++G(d,p) basis set were employed to compute their geometric optimization, fundamental frequencies and molecular parameters. The detected FT-IR and FT-Raman spectra were compared with their simulated spectra and the rms error between the detected and simulated vibrational frequencies was found at 6.17, 7.22 and 6.76 cm−1 for FMA, CMA and BMA, respectively. All the vibrational fundamentals were assigned unequivocally using potential energy distribution (PED) obtained in the computations. 1H and 13C NMR chemical shifts were evaluated by integrating the gauge-independent atomic orbital (GIAO) method with DFT and compared with corresponding experimental values. TD-DFT approach was followed to compare the simulated absorption maxima (λmax) in DMSO-d6 solvent with observed values and interpreted in terms of HOMO and LUMO. The global reactive descriptors were estimated from the associated energies of HOMO and LUMO which describe the reactivity and stability of the molecules. Molecular electrostatic potential (MEP) surface has been determined using the charge density distributions to demonstrate electrophilic and nucleophilic nature of the molecules. DFT computations also ascertained the applicability of the titled molecules as NLO materials from the computed values of dipole moment and hyperpolarizability. Thermodynamic parameters and rotational constants were also evaluated employing rigid rotor harmonic oscillator approximation. Natural bond orbital (NBO) analysis confirmed the charge delocalization due to intra-molecular interactions.

Glutamine-rich regions of the disordered CREB transactivation domain mediate dynamic intra- and intermolecular interactions.

The cyclic AMP response element (CRE) binding protein (CREB) is a transcription factor that contains a 280-residue N-terminal transactivation domain and a basic leucine zipper that mediates interaction with DNA. The transactivation domain comprises three subdomains, the glutamine-rich domains Q1 and Q2 and the kinase inducible activation domain (KID). NMR chemical shifts show that the isolated subdomains are intrinsically disordered but have a propensity to populate local elements of secondary structure. The Q1 and Q2 domains exhibit a propensity for formation of short β-hairpin motifs that function as binding sites for glutamine-rich sequences. These motifs mediate intramolecular interactions between the CREB Q1 and Q2 domains as well as intermolecular interactions with the glutamine-rich Q1 domain of the TATA-box binding protein associated factor 4 (TAF4) subunit of transcription factor IID (TFIID). Using small-angle X-ray scattering, NMR, and single-molecule Förster resonance energy transfer, we show that the Q1, Q2, and KID regions remain dynamically disordered in a full-length CREB transactivation domain (CREBTAD) construct. The CREBTAD polypeptide chain is largely extended although some compaction is evident in the KID and Q2 domains. Paramagnetic relaxation enhancement reveals transient long-range contacts both within and between the Q1 and Q2 domains while the intervening KID domain is largely devoid of intramolecular interactions. Phosphorylation results in expansion of the KID domain, presumably making it more accessible for binding the CBP/p300 transcriptional coactivators. Our study reveals the complex nature of the interactions within the intrinsically disordered transactivation domain of CREB and provides molecular-level insights into dynamic and transient interactions mediated by the glutamine-rich domains.

Ligand 1 H NMR Chemical Shifts as Accurate Reporters for Protein-Ligand Binding Interfaces in Solution.

The availability of high-resolution 3D structural information is crucial for investigating guest-host systems across a wide range of fields. In the context of drug discovery, the information is routinely used to establish and validate structure-activity relationships, grow initial hits from screening campaigns, and to guide molecular docking. For the generation of protein-ligand complex structural information, X-ray crystallography is the experimental method of choice, however, with limited information on protein flexibility. An experimentally verified structural model of the binding interface in the native solution-state would support medicinal chemists in their molecular design decisions. Here we demonstrate that protein-bound ligand 1 H NMR chemical shifts are highly sensitive and accurate probes for the immediate chemical environment of protein-ligand interfaces. By comparing the experimental ligand 1 H chemical shift values with those computed from the X-ray structure using quantum mechanics methodology, we identify significant disagreements for parts of the ligand between the two experimental techniques. We show that quantum mechanics/molecular mechanics (QM/MM) molecular dynamics (MD) ensembles can be used to refine initial X-ray co-crystal structures resulting in a better agreement with experimental 1 H ligand chemical shift values. Overall, our findings highlight the usefulness of ligand 1 H NMR chemical shift information in combination with a QM/MM MD workflow for generating protein-ligand ensembles that accurately reproduce solution structural data.

Bioactive ambuic acid congeners from endophytic fungus Pestalotiopsis trachicarpicola SC-J551.

New ambuic acid derivatives, pestallic acids R-V (1-5), together with ambuic acid (6), were isolated from the endophytic fungus Pestalotiopsis trachicarpicola SC-J551 derived from the fern Blechnum orientale L., of which compound 2, being racemic, was separated to two optically pure enantiomers (+)-2 and (-)-2. The structures including absolute configurations of these new compounds were elucidated by extensive spectroscopic analysis and theoretical simulations of their ECD spectra and 13C NMR chemical shifts. Compounds 1 and 3 exhibited cytotoxicity against human carcinoma A549, HeLa, HepG2, and MCF-7 cells (IC50: 3.6-12.5 μM) and compound 3 was also active against Staphylococcus aureus and MRSA (MIC = 20 μg ml-1). Compound (±)-2 showed inhibitory activity against LPS-induced NO release (IC50 = 21.1 μM) and t-BHP-induced ROS production (IC50 = 8.5 μM) in RAW264.7 macrophages.

Ring opening ring closure reactions with 5,9-diethyl-7-(chromon-3-yl)-7-hydroquinolino[3′,4′:5,6]pyrano[3,2-c]quinoline-6,8(5H,9H)-dione with some 1,2-binucleophiles: Synthesis, characterization, DFT study and biological activity

The chemical behaviour of electron deficient substrate 1 was investigated with some 1,2-bi-nucleophilic reagents. Reaction of substrate 1 with hydrazine derivatives namely hydrazine hydrate, phenylhydrazine, 7‑chloro-4-hydrazinoquinoline and 3-hydrazino-5,6-diphenyl-1,2,4-triazine led to 7-pyrazolylquinolinopyranoquinolines 2, 3, 6 and 7, respectively. These reactions proceed through γ-pyrone ring opening followed by pyrazole ring closure. Moreover, treating compound 1 with hydroxylamine hydrochloride provided 7-isoxazolylquinolino[3′,4′:5,6]pyrano[3,2-c]quinoline 8. The molecular structures were optimized utilizing DFT/B3LYP functional with 6–311G+(d,p) basis sets for all compounds. Moreover, global reactivity descriptors like chemical potential (μ), electronegativity (χ), hardness (η), softness (S) and electrophilicity index (ω) were computed to predict the chemical reactivity and kinetic stability of the synthesized compounds. The locations susceptible to attack by electrophiles and nucleophiles were examined at the same theoretical level by using molecular electrostatic potential (MEP) and condensed Fukui functions. The NMR chemical shifts were computed by the Gauge Independent Atomic Orbital (GIAO) method and compared to the experimental results. The first hyperpolarizability of the prepared compounds is higher than urea, so serves as good candidate for nonlinear optical (NLO) materials. The synthesized substances were tested for their efficacy as antimicrobial agents against a variety of bacterial and fungal species. Additionally, the present compounds revealed some antitumor activity (compounds 3 and 7 showed activity comparable to cis-platin, used as a reference drug in the assay). Furthermore, the synthesized compounds were moderately compliant with Lipinski's rule of five, suggesting that related compounds might be suitable for oral administration as medications.

Molecular structural analysis, conformers and spectral (FT-IR, FT-Raman, NMR and UV-Visible), Importance of solvent role in molecular, ADME and molecular docking investigation on alpha-cyano-4-hydroxycinnamic acid

The primary objective of research to reveals the effective drug treatment for corona virus disease (COVID-19). The current study on alpha-cyano-4-hydroxycinnamic acid (ACHC), the theoretical predictions were done by using Gaussian 09 W software on the basis of DFT/ TDFT/B3LYP methods with basis set of 6–311++G (d, p). The vibrational wavenumbers were obtained from the observed FT-IR and FT-Raman spectra and these vibrations were assigned on the basis of their potential energy distribution (PED) contribution. 1H and 13C NMR chemical shift of the molecule were computed by using Gauge independent atomic orbital (GIAO) method. In UV-Visible analysis the electronic transition was predicted by Time-dependent self-consistent field (TD-SCF)/DFT method. NBO analysis was done to understand the possible the intermolecular interaction, electron transition within the donor and acceptor orbitals of the molecule. The HOMO and LUMO indicates the prominent charge transfer possibilities and its energy gap shows stability of the molecule. A molecular electrostatic potential (MEP) image shows the electrophilic and nucleophilic sites of the molecule. Molecular docking analysis was carried out against Agaricus bisporus tyrosinase (2Y9X) and severe acute respiratory syndrome corona virus 2 (6LZG).

Investigation on the stability of the Enol Tautomer of Favipiravir and its derivatives by DFT, QTAIM, NBO, NLO and 1H-NMR

Relative stability energies of enol and keto forms of Favipiravir drug (6-fluoro-3-hydroxy-2-pyrazine carboxamide) and its twelve derivatives were theoretically envisaged using the B3LYP/6-311 + G(3df,2p)//B3LYP/6-311 + G(d,p) level of theory. Influence of the nature of the substituted groups on the geometric structures, IMHB, vibrational frequencies, dipole moments, and global reactivity descriptors was systematically studied. The enol form was found to be more stable than the keto form, regardless of the nature of the substituted group, by an average of 12.5 and 5.4 kcal/mol in the gas phase and in the aqueous solution, respectively. The role of the IMHB strength in the stability of the enol form compared with the keto form was investigated in terms of QTAIM and NBO analysis and 1H NMR chemical shifts. The NLO properties at CAM-B3LYP with 6-311 + G(d,p) basis set of the two forms and their derivatives were also used to explain the relative stability.

Experimental and theoretical comparison of the vibrational and NMR spectra of novel 6-6’-(1E-1’E)-(Propane-1,3Diylbis (Azanylyidene)) Bis (Phenylmethylylidene)) Bis (3-Octyloxy) Phenol), NBO and molecular docking studies

The characterization study of the synthesized novel compound 6-6’-(1E-1’E)-(Propane-1,3Diylbis(Azanylyidene))Bis(Phenylmethylylidene))Bis(3-Octyloxy)Phenol) (C45H58N2O4) was done by FT-IR, Raman and NMR spectra. Vibrational analysis was realized with normal coordinate treatment, and vibrational modes were assigned in the mid-IR region. The 13C and 1H -NMR spectra of the title compound were measured in DMSO and chloroform, and the corresponding chemical shifts were calculated in the different basis sets (6-31++G(d,p), 6-311G(2d,p), 6-311++G(2d,p), TZVPP) of DFT-B3LYP with continuum models. The vibrational and NMR spectroscopies show that the existence of the intramolecular resonance-assisted hydrogen bonds(O-H...N) results in the redshift of OH vibrational modes and its high proton chemical shifts (ca. 16 ppm), as confirmed by X-ray crystal structure and NRT studies.13C NMR chemical shifts of the Schiff base bond are determined as ca. 174 ppm. The calculations indicate that both the intramolecular hydrogen bond strength and the OH-proton chemical shift increase with increasing solvent polarity. The molecular docking studies reveal that the title ligand has the potency of inhibition against the VIM-2 and NDM-1 active sites of metallo-β-lactamase receptor.

1H, 31P NMR, Raman and FTIR spectroscopies for investigating phosphoric acid dissociation to understand phosphate ion kinetics in body fluids

The study investigates the formation and transportation of ionic charge carriers in phosphoric acid-water system. This investigation encompasses an analysis of 1H and 31P NMR chemical shifts, self-diffusion coefficients, spin-lattice relaxation rates, spin-spin relaxation rates, activation energies, dissociation constants, electrical conductivity, and Raman shifts, along with FTIR spectra across various water concentrations. Significantly, the maxima observed in these curves at around 0.8 water molar fraction predominantly from the unique molecular arrangement between phosphoric acid and water molecules, influenced by a hydrogen bonding network. These findings yield valuable insights into phosphate ion kinetics within body fluids, covering essential aspects like hydrogen bonding networks, ionization processes, and the energy kinetics of phosphoric dissociation. A customized semiempirical model is applied to calculate dissociated species (water, phosphoric acid, and hydronium ion) at different water contents within a wide range of water mole fraction. Furthermore, this investigation extends to the dissociation of phosphoric acid in DMEM cell culture media, offering a more precise model for phosphate ionic kinetics within body fluids, especially at nominal phosphate concentrations of approximately 1:700μL.

Synthesis, characterization, DFT, vibrational analysis (FT-IR and FT-Raman), topology and molecular docking studies of 3,3′-((1E,1′E)-((sulfonylbis(4,1-phenylene)) bis (azaneylylidene)) bis (methaneylylidene)) diphenol

The 3,3′-((1E,1′E)-((sulfonylbis(4,1-phenylene)) bis (azaneylylidene)) bis (methaneylylidene)) diphenol (D3H) was characterized by experimental and theoretical approaches. Titled compound FT-IR, FT-Raman, NMR (1H), UV–vis and fluorescence spectral analysis were developed in experimentally. After that, theoretical computations at the DFT/WB97XD/cc-pVDZ basis set level were carried out. The experimental geometrical parameters and the theoretical geometrical parameters were compared and well matched. The frequencies calculated using FT-Raman and FT-IR matched those obtained from experiments. The potential energy distributions analysis was calculated. Comparisons were made between the theoretical and experimental NMR chemical shifts. Absorption wavelengths in the UV–Vis spectrum were measured experimentally and compared to those predicted by TD-DFT. It is optical material, because its showed good fluorescence spectrum. The frontier molecular orbital, natural bond orbital analysis, molecular electrostatic potential, electron localized function, reduced density gradient and localized orbital locator, were carried out and thoroughly explained. According on the results of docking tests, the greatest possible binding energy score is -7.52 kcal/mol.

Interaction of carbon nanotube with anti-cancer drugs Busulfan and Mercaptopurine: A DFT study

In this research, the interactions of busulfan and mercaptopurine with single-walled carbon nanotubes (CNT) are investigated. The interaction of the drugs busulfan and mercaptopurine with carbon nanotube has been studied by DFT method. The chosen drugs, CNT(6,6–6), CNT/drug complexes, and their electronic properties are studied using the B3LYP/6-31G(d,p) method in the gas phase. The electronic transition is also calculated with the use of TD-DFT method. NMR Chemical shift, NBO, FMO calculations are implemented. DOS plotsand MEPare obtained for every complex. Natural bond orbital (NBO) study indicates charge transfer have occurredbetween drug molecules and CNT(6,6–6). TD-DFT results revealed the HOMO and LUMO states energy gaps of busulfan and mercaptopurine are 8.94 eV and 5.27 eV respectively, but after interaction with carbon-nanotube they are reduced to 1.63 eV and 1.74 eV. These results revealed that both complexes are favorable. Busulfan strongly interacts with carbon nanotube compare to mercaptopurine.

A Novel Anthraquinone-Based Azo Compound: Synthesis, Quantum Chemical Calculations and Investigation of ADMET Properties

This study involved the synthesis of the potentially drug candidate 2-((9,10-dioxo-9,10-dihydroanthracen-2-yl)diazenyl)-5-hydroxybenzoic acid (DHA), the elucidation of its structure using spectroscopic techniques and the determination of the compound's lowest energy structure using the DFT/B3LYP method and the 6-311G(d,p) basis set. The compound's vibration frequencies and NMR chemical shift values were then determined using optimized geometry. The three-dimensional molecular electrostatic potential (MEP) map of the compound and the HOMOs-LUMOs and molecular orbital energies were examined using the DFT approach. The compound's ADMET properties were then determined, and its potential for usage as a drug was assessed. Additionally, the predicted toxicity class and LD50 value for the DHA were established. The outcomes demonstrated that by having ADMET properties, this newly synthesized compound has the potential to be a drug.