PREPRINT RESEARCHGATE.NET OCTOBER 1, 2021 1 Infrared Spectroscopy of the two esters from 2,3,4,5-Tetrahydro-oxepine derivatives, new nano molecules Ricardo Gobato 1,* , Alireza Heidari 2 , Lauro Figueroa Valverde 3 Abhijit Mitra 4 , Marcela Rosas Nexticapa 5 , Maria López Ramos 3 , Maria Virginia del Socorro Mateu Armad 5 , Magdalena Alvarez Ramirez 5 , Francisco Díaz Cedillo 6 , Ibtihal Kadhim Kareem Dosh 7 1 Green Land Landscaping and Gardening, Seedling Growth Laboratory, 86130-000, Parana, Brazil. 2 Faculty of Chemistry, California South University, 14731 Comet St. Irvine, CA 92604, USA, United States of America. 3 University Autonomous of Campeche (Faculty of Chemical-Biological Sciences), Calle Av. Agustín Melgar s/n, Buenavista, 24039 Campeche, Mexico. 4 Department of Marine Science, University of Calcutta, 35 B. C Road, Kolkata, 700019, West Bengal, India. 5 Facultad de Nutrición, Universidad Veracruzana, Médicos y Odontologos s/n C.P. 91010, Unidad del Bosque, Xalapa, Veracruz, Mexico. 6 Escuela Nacional de Ciencias Biológicas del Instituto Politécnico Nacional. Prol. Carpio y Plan. de Ayala s/n Col. Santo Tomas, D.F. C.P. 11340, Mexico. 7 Kufa University, Faculty of Education, Department of Chemistry, An Najaf, Iraq. * Corresponding author: ricardogobato@hotmail.com; ricardogobato@gardener.com Abstract—The work focused on determining the Infrared spectroscopy (IRS) of the two compounds calculated are from two esters (compounds C1 and C2) from 2,3,4,5-Tetrahydro- oxepine derivatives, here called C1 and C2. The IRS was obtained via computational methods ab initio Restricted Hartree-Fock. Optimization of molecular structure via UFF, followed by PM3, RHF/EPR-II and RHF/STO-6G, thus obtaining a stable struc- ture, in STP. The molecule was obtained, whose composition is C: 81.7%; H: 7.1%; N: 3.4%; O: 7.8%, 411.53536 g, and molecular formula: C28H29NO2, for C1 and C: 70.6%; H: 7.4%; N: 10.3%; O: 11.7%, 544.68439 g, and molecular formula: C32H40N4O4. The highest vibrational absorbance frequency peaks for the C1 and C2 molecule are found at the frequency of 1793.58 cm -1 , 1867.14 cm -1 and 1956.39 cm -1 , for C1 and 1368.99 cm -1 , 1409.43 cm -1 and 1790.47 cm -1 , for C2, respectively. Limitations our study has so far been limited to computational simulation via quantum mechanics (QM) an applied theory. Our results and calculations are compatible with the theory of QM. Index Terms—Restricted Hartree-Fock method, Infrared spec- troscopy, IR spectroscopy, UFF, PM3, EPR-II. I. I NTRODUCTION T He Infrared spectroscopy (IRS) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. The method or technique of IRS is conducted with an instrument called spectrophotometer which produces an IRS. An IRS can be visualized in a graph of infrared light absorbance (or transmittance) on the vertical axis vs. frequency or wavelength on the horizontal axis. [1], [2], [3] The work focused on determining the IRS [1], [2], [3] of the three compounds here named C1 and C2, where the IRS was obtained via computational methods ab initio Restricted Hartree-Fock. [4], [5], [6], [7], [8], [9], [10], [11], [12], [13] [14], [15], [16]. The molecules was obtained experimentally in the labo- ratory of the University Autonomous of Campeche (Faculty of Chemical-Biological Sciences) Valverde et al. [17], [18], [19], [20], [21] and are characterized by two-ester structures: 2,3,4,5-Tetrahydro-oxepine derivatives, compounds C1 and C2. II. METHODS A. Methodology Its structure and chemical conformation and its IRS were obtained from computational chemistry calculations, using the GAMESS software. [15], [22] The methods used initially were UFF (Universal Force Field) [23], [24], [22], [25], obtaining the lowest energy molecular structure. Optimization of molecular structure via UFF, followed by PM3 (Parametric Method 3) [26], [27], [28], [29], followed by Restricted Hartree-Fock [4], [5], [6], [7], [8], [9], [10], [11], [12], [13] [14], [15], [16] RHF/EPR-II