Spectroscopic studies, DFT calculation, electronic properties and antimicrobial studies.

What is it about?

We report the 2-(2-(naphthalene-2-yloxy)-1-phenylethylidene) hydrazinecarboxamide (NAPCAR) compound has been synthesized from 2-(naphthalene-2-yloxy)-1-phenylethanone (2-NAPETH), the parent compound. The characterization of both the parent and product has been done using FT-IR, 1H NMR and 13C NMR spectroscopic and theoretical studies. Solid double bonds have been identified near some of the aromatic ring carbons instead of the partial double bond in both the parent and the title compounds. The Highest Occupied Molecular Orbital (HOMO) is found to be concentrated mainly on the naphthyl ring in both 2- NAPETH and NAPCAR. However, major portion of Lowest Unoccupied Molecular Orbital (LUMO) has been found to be spread over the naphthyl ring of NAPCAR unlike the2- NAPETH which has LUMO on the benzyl ring. The electrostatic potential surface (ESP) shows that both the 2- NAPETH and NAPCAR have nucleophilic site only. This NAPCAR is found to be against the pathogenic bacteria and fungi indicating that this compound may be considered as a candidate to be used in the development of new drugs capable of treating microbial infections.

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Why is it important?

Density Functional Theory (DFT) is the most important methodology for theoretically predicting the behaviors of organic compounds. This provides an excellent clarity on the geometry, molecular polarization, atomic charge distribution, dipole moment derivatives of bonds, structural and dynamic aspects, and vibrational frequencies [1]. Semicarbazones fall into the class of organic molecules (General Structure: R-C = NNHCONH2) that have attracted growing interest among the researchers due to their versatile use in industry. These are important compounds for researchers because of their excellent coordination behavior, analytical applications [2], [3], [4] and antibacterial activities [5], [6]. Semicarbazones and their derivatives have been used in synthetic chemistry, medicinal chemistry, polymers [7], [8] and herbicides. They have lone pair electron containing nitrogen and oxygen/sulphur donor atoms [9], [10], [11], [12]. Semicarbazone derivatives are usually prepared through the reaction of aldehydes/ketones with semicarbazide hydrochloride (NH2NHCONH2) with an acid or a base as catalyst. [13], [14] Boudebbous et al. [15] have reported synthesis, crystal structure, biological evaluation, docking study and DFT calculations of 1-amidoalkyl-2-naphthol derivative. The newly synthesized 1-(pyridine-2-yl amino) methyl naphthalene-2-ol molecules have been characterized using spectroscopic, computational and molecular docking studies by Rajamani et al. [16]. Literature reports show that the synthesis of semicarbazones is done mostly using reagents and synthetic method which are toxic and harmful to the environment. Alternate synthesis method, the green chemistry in which non-toxic reagents that are also harmless to the environment are used, is not only simple to be applied and reduces the pollution to a greater extent but, comparatively cheaper. This is a solvent-free organic synthesis method which are largely green [17], [18], [19], [20], [21], [22], [23], [24], [25], [26], [27], [28], [29], [30], [31]. Therefore, the solid-state synthesis method which is the green approach has been adopted in the present work to synthesize the title compound which has been characterized by spectroscopic (FT-IR, 1H NMR, 13C NMR) methods. In the present study, we report the solvent-free synthesis and detailed spectroscopic investigation on 2-(2-(naphthalene-2-yloxy)-1-phenylethylidene) hydrazine carboxamide (NAPCAR). Literature survey reveals that so far there is no experimental and theoretical study on this NAPCAR. Structural and bonding features reveal that this NAPCAR molecule has several reactive groups which can participate in intermolecular hydrogen bonding instigating interactions with biological targets. Theoretically NAPCAR molecule is studied using B3LYP/6-311++G (2d.2p) level of the Density Functional Theory. Several properties like molecular geometry, HOMO – LUMO energies, Molecular Electrostatic potential analysis of the NAPCAR are carry out to clear the information about charge donating/accepting nature of the molecule. Antimicrobial activity of NAPCAR molecule was also analyzed.

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