María J. Álvarez-Pérez, Carlos A. Padilla-Jaramillo, B.Sc., Luis M. Díaz-Sánchez, M.Sc., Marianny Y. Combaiza, PhD., Cristian Blanco-Tirado, PhD., and Aldo F. Combariza, PhD. 1. Departamento de Biología, Universidad de Sucre, Sincelejo, 700001, Colombia. 2. Escuela de Química, Universidad Industrial de Santander, Bucaramanga, 680002, Bucaramanga, Colombia. S w e e t e n i n g t h e c h e m i s t r y w o r l d w i t h s p r i n k l e s o f q u a n t u m b i o l o g y Proton and Cation Affinities of Biosignature phytoplankton pigments and MALDI matrices from RI-MP2 quantum calculations Phytoplankton is a bioindicator useful to measure environmental health. Pigment-Biosignature compounds detection for these organisms by MALDI MS, allows its chemotaxonomic identiﬁcation. Feasible MALDI matrices with thermochemical features (Proton/Cation Affinities -PA/CA- and Ionization Energies -Ei-) guarantees a satisfactory ionization process. So, to establish these properties is a topical issue. We used quantum chemical methods (HF and Pos-HF) to calculate PA/CA energies of MALDI matrices and biosignature pigments. Ⓞ Ⓥ Ⓔ Ⓡ Ⓥ Ⓘ Ⓔ Ⓦ Geometry Optimization Aquatic Ecosystem Vibrational Frequency Electrostatic Maps MALDI MS and Proton/Cation matrices Löwding Charge Analysis δ+ δ- Acknowledgments ●Universidad Nacional de San Agustín (UNSA), Arequipa, Perú for providing access to INKARI cluster facilitis, located at the Observatorio Astronómica Pedro Paulet. ●Thanks to Guatiguara Technology Park and the Central Research Laboratory Facility at Industrial University of Santander for infrastructural support. ●We also acknowledge a graduate fellowship and ﬁnancial support from SGR- BPIN: 2019000100020 and VIE-UIS project 2815 - 2021. Conclusions Geometry Setup protocol is feasible for our systems, and IR spectra are in agreement with experimental reports. From MEP it would be ideal to perform a Löwding population analysis for determining the protonation sites and associated charge. Next step is to optimize and calculate the SPE to build cation-structures. References ● Denis, Elizabeth H.2022, et al. Proton Affinity Values of Fentanyl and Fentanyl Analogues Pertinent to Ambient Ionization and Detection. Journal of the American Society for Mass ● Padilla Jaramillo, C.A., Díaz Sánchez, L.M. , Combariza Montañez, M.Y. , Blanco Tirado, C. y Combariza Montañez, A.F. 2021. Photon Harvesting Molecules: Ionization Potential from Quantum Chemical Calculations of Phytoplanktonic Pigments for MALDI-MS Analysis. Orinoquia. 25, 1 (jun. 2021), 13–23. DOI:https://doi.org/10.22579/20112629.676. ● Gross, H. J., 2017. Mass Spectrometry.Third Edition. ISBN 978-3-319-54397-0. Springer International Publishing.DOI 10.1007/978-3-319-54398-7 Optimization Method: RI-MP2 Basis set: Def2-TZVP ETol: 1E-08 a.u. MEP maps Method: RI-MP2 Basis set: Def2-SVP IsoValue: 0.004 PS: Protonation Site PS PS PS -0.167 -0.037 -0.052 -0.058 𝛼-CHCA 𝛼-CHCA Method: RI-MP2 Basis set: Def2-TZVP Grapher: XMGRACE Avoiding negative frequencies and comparing the IR spectral The overlapped experimental and calculated IR have good agreement Proton Enthalpy Reaction Zero Point Energy Protonated - Ground Electronic Energy Protonated - Ground Gas Constant Absolute Temperature PS ID: Phys50