{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,10,12]],"date-time":"2025-10-12T00:22:31Z","timestamp":1760228551801,"version":"build-2065373602"},"reference-count":55,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2022,5,19]],"date-time":"2022-05-19T00:00:00Z","timestamp":1652918400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Ministry of Science and Higher Education of the Russian Federation","award":["14.W03.31.0034"],"award-info":[{"award-number":["14.W03.31.0034"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Spiro-substituted nitroxyl biradicals are widely used as reagents for dynamic nuclear polarization (DNP), which is especially important for biopolymer research. The main criterion for their applicability as polarizing agents is the value of the spin\u2013spin exchange interaction parameter (J), which can vary considerably when different couplers are employed that link the radical moieties. This paper describes a study on biradicals, with a ferrocene-1,1\u2032-diyl-substituted 1,3-diazetidine-2,4-diimine coupler, that have never been used before as DNP agents. We observed a substantial difference in the temperature dependence between Electron Paramagnetic Resonance (EPR) spectra of biradicals carrying either methyl or spirocyclohexane substituents and explain the difference using Density Functional Theory (DFT) calculation results. It was shown that the replacement of methyl groups by spirocycles near the N-O group leads to an increase in the contribution of conformers having J \u2248 0. The DNP gain observed for the biradicals with methyl substituents is three times higher than that for the spiro-substituted nitroxyl biradicals and is inversely proportional to the contribution of biradicals manifesting the negligible exchange interaction. The effects of nucleophiles and substituents in the nitroxide biradicals on the ring-opening reaction of 1,3-diazetidine and the influence of the ring opening on the exchange interaction were also investigated. It was found that in contrast to the methyl-substituted nitroxide biradical (where we observed the ring-opening reaction upon the addition of amines), the ring opening does not occur in the spiro-substituted biradical owing to a steric barrier created by the bulky cyclohexyl substituents.<\/jats:p>","DOI":"10.3390\/molecules27103252","type":"journal-article","created":{"date-parts":[[2022,5,20]],"date-time":"2022-05-20T00:18:11Z","timestamp":1653005891000},"page":"3252","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Effects of Spiro-Cyclohexane Substitution of Nitroxyl Biradicals on Dynamic Nuclear Polarization"],"prefix":"10.3390","volume":"27","author":[{"given":"Nargiz B.","family":"Asanbaeva","sequence":"first","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Larisa Yu.","family":"Gurskaya","sequence":"additional","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1770-1968","authenticated-orcid":false,"given":"Yuliya F.","family":"Polienko","sequence":"additional","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2398-5271","authenticated-orcid":false,"given":"Tatyana V.","family":"Rybalova","sequence":"additional","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2869-1777","authenticated-orcid":false,"given":"Maxim S.","family":"Kazantsev","sequence":"additional","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6260-8124","authenticated-orcid":false,"given":"Alexey A.","family":"Dmitriev","sequence":"additional","affiliation":[{"name":"V.V. Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3 Institutskaya Str., Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2263-1300","authenticated-orcid":false,"given":"Nina P.","family":"Gritsan","sequence":"additional","affiliation":[{"name":"V.V. Voevodsky Institute of Chemical Kinetics and Combustion, SB RAS, 3 Institutskaya Str., Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Nadia","family":"Haro-Mares","sequence":"additional","affiliation":[{"name":"TU Darmstadt, Eduard-Zintl-Institute for Inorganic and Physical Chemistry, Alarich-Weiss-Stra\u00dfe 8, 64287 Darmstadt, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6214-2272","authenticated-orcid":false,"given":"Torsten","family":"Gutmann","sequence":"additional","affiliation":[{"name":"TU Darmstadt, Eduard-Zintl-Institute for Inorganic and Physical Chemistry, Alarich-Weiss-Stra\u00dfe 8, 64287 Darmstadt, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1304-9762","authenticated-orcid":false,"given":"Gerd","family":"Buntkowsky","sequence":"additional","affiliation":[{"name":"TU Darmstadt, Eduard-Zintl-Institute for Inorganic and Physical Chemistry, Alarich-Weiss-Stra\u00dfe 8, 64287 Darmstadt, Germany"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1540-7033","authenticated-orcid":false,"given":"Evgeny V.","family":"Tretyakov","sequence":"additional","affiliation":[{"name":"N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 47 Leninsky Prosp., Moscow 119991, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0057-383X","authenticated-orcid":false,"given":"Elena G.","family":"Bagryanskaya","sequence":"additional","affiliation":[{"name":"N.N. Vorozhtsov Institute of Organic Chemistry, Siberian Branch of Russian Academy of Sciences (SB RAS), 9 Acad. Lavrentiev Avenue, Novosibirsk 630090, Russia"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2022,5,19]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1146\/annurev-physchem-071119-040222","article-title":"High-Field Dynamic Nuclear Polarization","volume":"71","author":"Corzilius","year":"2020","journal-title":"Annu. Rev. Phys. Chem."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/bs.arnmr.2018.12.001","article-title":"Solid-State NMR of Nanocrystals","volume":"97","author":"Gutmann","year":"2019","journal-title":"Annu. Reports NMR Spectrosc."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"116","DOI":"10.1016\/j.ssnmr.2019.05.009","article-title":"Recent Developments in MAS DNP-NMR of Materials","volume":"101","author":"Rankin","year":"2019","journal-title":"Solid State Nucl. Magn. Reson."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"63","DOI":"10.1016\/j.cocis.2018.02.006","article-title":"Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy (DNP SENS): Principles, Protocols, and Practice","volume":"33","author":"Liao","year":"2018","journal-title":"Curr. Opin. Colloid Interface Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.cocis.2017.11.002","article-title":"Optimal Sample Formulations for DNP SENS: The Importance of Radical-Surface Interactions","volume":"33","author":"Perras","year":"2018","journal-title":"Curr. Opin. Colloid Interface Sci."},{"key":"ref_6","first-page":"120","article-title":"Dynamic Nuclear Polarization for Sensitivity Enhancement in Modern Solid-State NMR","volume":"102\u2013103","author":"Wittmann","year":"2017","journal-title":"Prog. Nucl. Magn. Reson. Spectrosc."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"583","DOI":"10.1002\/mrc.4688","article-title":"DNP-Enhanced Solid-State NMR Spectroscopy of Active Pharmaceutical Ingredients","volume":"56","author":"Zhao","year":"2018","journal-title":"Magn. Reson. Chem."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"14287","DOI":"10.1021\/ja304918g","article-title":"Water-Soluble Narrow-Line Radicals for Dynamic Nuclear Polarization","volume":"134","author":"Haze","year":"2012","journal-title":"J. Am. Chem. Soc."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"13121","DOI":"10.1039\/D0CC04920D","article-title":"Water-Soluble BDPA Radicals with Improved Persistence","volume":"56","author":"Mandal","year":"2020","journal-title":"Chem. Commun."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"5598","DOI":"10.1002\/chem.201504693","article-title":"Tailoring of Polarizing Agents in the BTurea Series for Cross-Effect Dynamic Nuclear Polarization in Aqueous Media","volume":"22","author":"Casano","year":"2016","journal-title":"Chem. A Eur. J."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"16587","DOI":"10.1021\/jacs.0c04911","article-title":"Open and Closed Radicals: Local Geometry around Unpaired Electrons Governs Magic-Angle Spinning Dynamic Nuclear Polarization Performance","volume":"142","author":"Stevanato","year":"2020","journal-title":"J. Am. Chem. Soc."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"11422","DOI":"10.1021\/acs.jpcc.8b02570","article-title":"Novel Biradicals for Direct Excitation Highfield Dynamic Nuclear Polarization","volume":"122","author":"Bothe","year":"2018","journal-title":"J. Phys. Chem. C"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"13340","DOI":"10.1021\/jacs.8b08081","article-title":"BDPA-Nitroxide Biradicals Tailored for Efficient Dynamic Nuclear Polarization Enhanced Solid-State NMR at Magnetic Fields up to 21.1 T","volume":"140","author":"Wisser","year":"2018","journal-title":"J. Am. Chem. Soc."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"5648","DOI":"10.1021\/ja1109002","article-title":"High-Field Dynamic Nuclear Polarization with High-Spin Transition Metal Ions","volume":"133","author":"Corzilius","year":"2011","journal-title":"J. Am. Chem. Soc."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"1942","DOI":"10.1021\/ar300322x","article-title":"Dynamic Nuclear Polarization Surface Enhanced NMR Spectroscopy","volume":"46","author":"Rossini","year":"2013","journal-title":"Acc. Chem. Res."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"52211","DOI":"10.1063\/1.2833582","article-title":"Dynamic Nuclear Polarization at High Magnetic Fields","volume":"128","author":"Maly","year":"2008","journal-title":"J. Chem. Phys."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"550","DOI":"10.1039\/C5SC02921J","article-title":"Rational Design of Dinitroxide Biradicals for Efficient Cross-Effect Dynamic Nuclear Polarization","volume":"7","author":"Kubicki","year":"2016","journal-title":"Chem. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"4996","DOI":"10.1002\/anie.200805940","article-title":"Dynamic Nuclear Polarization with a Rigid Biradical","volume":"48","author":"Matsuki","year":"2009","journal-title":"Angew. Chemie Int. Ed."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"10858","DOI":"10.1002\/anie.201304657","article-title":"Highly Efficient, Water-Soluble Polarizing Agents for Dynamic Nuclear Polarization at High Frequency","volume":"52","author":"Rosay","year":"2013","journal-title":"Angew. Chemie Int. Ed."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Kathirvelu, V., Smith, C., Parks, C., Mannan, M.A., Miura, Y., Takeshita, K., Eaton, S.S., and Eaton, G.R. (2009). Relaxation Rates for Spirocyclohexyl Nitroxyl Radicals Are Suitable for Interspin Distance Measurements at Temperatures up to about 125 K. Chem. Commun., 454\u2013456.","DOI":"10.1039\/B817758A"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"12790","DOI":"10.1021\/ja405813t","article-title":"Large Molecular Weight Nitroxide Biradicals Providing Efficient Dynamic Nuclear Polarization at Temperatures up to 200 K","volume":"135","author":"Zagdoun","year":"2013","journal-title":"J. Am. Chem. Soc."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1016\/j.tetlet.2016.12.068","article-title":"A Nitroxide Diradical Containing a Ferrocen-1,1\u2032-Diyl-Substituted 1,3-Diazetidine-2,4-Diimine Coupler","volume":"58","author":"Bagryanskaya","year":"2017","journal-title":"Tetrahedron Lett."},{"key":"ref_23","first-page":"1","article-title":"Tuning the Properties of Nitroxide Spin Labels for Use in Electron Paramagnetic Resonance Spectroscopy through Chemical Modification of the Nitroxide Framework","volume":"25","author":"Haugland","year":"2017","journal-title":"Electron Paramagn. Reson."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"8016","DOI":"10.1021\/jo301235j","article-title":"Synthesis of 2,5-Bis(Spirocyclohexane)-Substituted Nitroxides of Pyrroline and Pyrrolidine Series, Including Thiol-Specific Spin Label: An Analogue of MTSSL with Long Relaxation Time","volume":"77","author":"Kirilyuk","year":"2012","journal-title":"J. Org. Chem."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"5778","DOI":"10.1002\/chem.200903102","article-title":"A Spirocyclohexyl Nitroxide Amino Acid Spin Label for Pulsed EPR Spectroscopy Distance Measurements","volume":"16","author":"Rajca","year":"2010","journal-title":"Chem. A Eur. J."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1264","DOI":"10.1021\/jo00267a009","article-title":"Reactivity of 1,3-Diaryl-2,4-Bis(Heteroarylimino)-1,3-Diazetidines. Formation of N1,N2,N3,N4,N5-Pentasubstituted Biguanides","volume":"54","author":"Molina","year":"1989","journal-title":"J. Org. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"13569","DOI":"10.1039\/D0CP02051F","article-title":"Balancing Dipolar and Exchange Coupling in Biradicals to Maximize Cross Effect Dynamic Nuclear Polarization","volume":"22","author":"Equbal","year":"2020","journal-title":"Phys. Chem. Chem. Phys."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1070\/RC2009v078n11ABEH004093","article-title":"The Chemistry of Nitroxide Radicals in the Molecular Design of Magnets","volume":"78","author":"Tretyakov","year":"2009","journal-title":"Russ. Chem. Rev."},{"key":"ref_29","first-page":"1","article-title":"Continuous Wave Electron Paramagnetic Resonance of Nitroxide Biradicals in Fluid Solution","volume":"47A","author":"Eaton","year":"2018","journal-title":"Concepts Magn. Reson. Part A Bridg. Educ. Res."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.jmr.2005.08.013","article-title":"EasySpin, a Comprehensive Software Package for Spectral Simulation and Analysis in EPR","volume":"178","author":"Stoll","year":"2006","journal-title":"J. Magn. Reson."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"RCR5025","DOI":"10.1070\/RCR5025","article-title":"Conjugated Nitroxides","volume":"91","author":"Tretyakov","year":"2022","journal-title":"Russ. Chem. Rev."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1021\/ct1006136","article-title":"DFT Calculations of Isotropic Hyperfine Coupling Constants of Nitrogen Aromatic Radicals: The Challenge of Nitroxide Radicals","volume":"7","author":"Hermosilla","year":"2011","journal-title":"J. Chem. Theory Comput."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2418","DOI":"10.1021\/acs.jpcc.6b13087","article-title":"Directly vs Indirectly Enhanced 13C in Dynamic Nuclear Polarization Magic Angle Spinning NMR Experiments of Nonionic Surfactant Systems","volume":"121","author":"Hoffmann","year":"2017","journal-title":"J. Phys. Chem. C"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"5145","DOI":"10.1021\/acs.jpcc.9b10504","article-title":"Direct and Indirect Dynamic Nuclear Polarization Transfer Observed in Mesoporous Materials Impregnated with Nonionic Surfactant Solutions of Polar Polarizing Agents","volume":"124","author":"Hoffmann","year":"2020","journal-title":"J. Phys. Chem. C"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"106688","DOI":"10.1016\/j.jmr.2020.106688","article-title":"Heteronuclear Cross-Relaxation Effect Modulated by the Dynamics of N-Functional Groups in the Solid State under 15N DP-MAS DNP","volume":"312","author":"Park","year":"2020","journal-title":"J. Magn. Reson."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"4863","DOI":"10.1002\/anie.201811941","article-title":"Complex Formation of the Tetracycline-Binding Aptamer Investigated by Specific Cross-Relaxation under DNP","volume":"58","author":"Aladin","year":"2019","journal-title":"Angew. Chemie Int. Ed."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"16572","DOI":"10.1021\/jacs.6b08683","article-title":"Heteronuclear Cross-Relaxation under Solid-State Dynamic Nuclear Polarization","volume":"138","author":"Daube","year":"2016","journal-title":"J. Am. Chem. Soc."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"5896","DOI":"10.1021\/ja00171a049","article-title":"Nuclear Overhauser Effect in Solids","volume":"112","author":"White","year":"1990","journal-title":"J. Am. Chem. Soc."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"154104","DOI":"10.1063\/1.3382344","article-title":"A Consistent and Accurate Ab Initio Parametrization of Density Functional Dispersion Correction (DFT-D) for the 94 Elements H-Pu","volume":"132","author":"Grimme","year":"2010","journal-title":"J. Chem. Phys."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"908","DOI":"10.1021\/ct800047t","article-title":"All-Electron Scalar Relativistic Basis Sets for Third-Row Transition Metal Atoms","volume":"4","author":"Pantazis","year":"2008","journal-title":"J. Chem. Theory Comput."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1787","DOI":"10.1002\/jcc.20495","article-title":"Semiempirical GGA-Type Density Functional Constructed with a Long-Range Dispersion Correction","volume":"27","author":"Grimme","year":"2006","journal-title":"J. Comput. Chem."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3098","DOI":"10.1103\/PhysRevA.38.3098","article-title":"Density-Functional Exchange-Energy Approximation with Correct Asymptotic Behavior","volume":"38","author":"Becke","year":"1988","journal-title":"Phys. Rev. A"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"8822","DOI":"10.1103\/PhysRevB.33.8822","article-title":"Density-Functional Approximation for the Correlation Energy of the Inhomogeneous Electron Gas","volume":"33","author":"Perdew","year":"1986","journal-title":"Phys. Rev. B"},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"242","DOI":"10.1016\/S0009-2614(97)00651-9","article-title":"Toward Reliable Adiabatic Connection Models Free from Adjustable Parameters","volume":"274","author":"Adamo","year":"1997","journal-title":"Chem. Phys. Lett."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"223","DOI":"10.1016\/S0009-2614(00)00166-4","article-title":"Ab Initio Computations of Effective Exchange Integrals for H\u2013H, H\u2013He\u2013H and Mn2O2 Complex: Comparison of Broken-Symmetry Approaches","volume":"319","author":"Soda","year":"2000","journal-title":"Chem. Phys. Lett."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"5648","DOI":"10.1063\/1.464913","article-title":"Density-functional Thermochemistry. III. The Role of Exact Exchange","volume":"98","author":"Becke","year":"1993","journal-title":"J. Chem. Phys."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"785","DOI":"10.1103\/PhysRevB.37.785","article-title":"Development of the Colle-Salvetti Correlation-Energy Formula into a Functional of the Electron Density","volume":"37","author":"Lee","year":"1988","journal-title":"Phys. Rev. B"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"e1327","DOI":"10.1002\/wcms.1327","article-title":"Software Update: The ORCA Program System, Version 4.0","volume":"8","author":"Neese","year":"2018","journal-title":"Wiley Interdiscip. Rev. Comput. Mol. Sci."},{"key":"ref_49","first-page":"128","article-title":"Suppression of Signals from the Probe in Bloch Decay Spectra","volume":"80","author":"Cory","year":"1988","journal-title":"J. Magn. Reson."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"131","DOI":"10.1016\/j.jmr.2010.12.011","article-title":"Straightforward, Effective Calibration of SPINAL-64 Decoupling Results in the Enhancement of Sensitivity and Resolution of Biomolecular Solid-State NMR","volume":"209","author":"Comellas","year":"2011","journal-title":"J. Magn. Reson."},{"key":"ref_51","unstructured":"Sheldrick, G.M. (1996). SADABS, Program for Empirical Absorption Correction of Area Detector Data, University of Gottingen."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"112","DOI":"10.1107\/S0108767307043930","article-title":"A Short History of SHELX","volume":"64","author":"Sheldrick","year":"2008","journal-title":"Acta Crystallogr. Sect. A"},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"3","DOI":"10.1107\/S2053229614024218","article-title":"Crystal Structure Refinement with SHELXL","volume":"71","author":"Sheldrick","year":"2015","journal-title":"Acta Crystallogr. Sect. C Struct. Chem."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"148","DOI":"10.1107\/S090744490804362X","article-title":"Structure Validation in Chemical Crystallography","volume":"65","author":"Spek","year":"2009","journal-title":"Acta Crystallogr. D Biol. Crystallogr."},{"key":"ref_55","doi-asserted-by":"crossref","first-page":"7384","DOI":"10.1021\/jp953141+","article-title":"Intermolecular Nonbonded Contact Distances in Organic Crystal Structures: Comparison with Distances Expected from van Der Waals Radii","volume":"100","author":"Rowland","year":"1996","journal-title":"J. Phys. Chem."}],"container-title":["Molecules"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/10\/3252\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,10]],"date-time":"2025-10-10T23:14:38Z","timestamp":1760138078000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1420-3049\/27\/10\/3252"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2022,5,19]]},"references-count":55,"journal-issue":{"issue":"10","published-online":{"date-parts":[[2022,5]]}},"alternative-id":["molecules27103252"],"URL":"https:\/\/doi.org\/10.3390\/molecules27103252","relation":{},"ISSN":["1420-3049"],"issn-type":[{"type":"electronic","value":"1420-3049"}],"subject":[],"published":{"date-parts":[[2022,5,19]]}}}