Special Issue Preface Cite This: J. Phys. Chem. A 2018, 122, 5671−5672
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Tribute to Manuel Yáñ ez and Otilia Mó
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Published as part of The Journal of Physical Chemistry virtual special issue “Manuel Yáñez and Otilia Mó Festschrift”. contact with the most advanced computational methods, that would significantly mark their research activities in the following years. Back to UAM in 1976, they started their own research lines. 1978 is a landmark year in their career: they published their first two contributions in the Journal of the American Chemical Society, which marked the opening of two research lines that they developed during their entire scientific career: the study of gas-phase basicities and the study of hydrogen bonds. This same year they started a third research line devoted to the study of atomic collisions and the description of autoionizing states in molecules. In the 1980s, they got important achievements along these three lines, which we briefly summarize below. More than 30 articles were produced in the following 10 years exploring the gas-phase proton affinities of a large number of compounds: monosubstituted benzenes, indol, indazole and azaindioles derivatives, imidazoles and pyrazoles, among others. They established the relationship between molecular charge distributions and proton affinities and explored the influence of the tautomerization processes in the gas-phase basicity. They further extended these studies to the basicity toward other Lewis acids, as alkaline monocations, and to the use of electrostatic potentials and the topological analysis of the charge density to predict the gas-phase basicity toward metal cations. In parallel, these early years saw the birth of hydrogen bond studies. This line of researched continued in the following decades, in collaboration with the group of J. Elguero and I. Alkorta, exploring in a systematic way the characteristics of noncovalent interaction in a large variety of systems. Their seminal work in water trimers established for the first time the existence of cooperative effects, nowadays being their most cited article. This study was extended to more complex systems as methanol, mixed methanol−water, or phosponic acid clusters. Also, they explored intramolecular hydrogen bonds in systems like thiomalonaldehyde, enols of β-diketones, and their nitrogen counterparts showing the existence of resonance assisted hydrogen bonds (RAHB). In these studies, they established the relationship between the strength of the hydrogen bonds and the topology of the charge density. One important part of this research was done in a long-standing collaboration with J. del Bene, which allowed them to determine the spin−spin coupling constants across a series of different kinds of hydrogen bonds. These couplings were used to determine the existence or not of RAHB in a variety of systems. In the last decades, such studies were extended to explore chalcogen−chalcogen interactions, systems showing X···H···Y intramolecular hydrogen bonds and X···Y chalcogen− chalcogen interactions (X = O, S; Y = Se, Te), in particular
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hemistry was born in the gas phase, not in solution. Indeed, many chemical reactions responsible for the formation of molecular precursors that later evolved into more complex molecular systems, including those at the origin of life, occurred in the early universe, when the interstellar medium was primarily in the gas phase. On top of that, chemical reactions occurring in the gas phase affect our everyday lives as much as those occurring in solution, for example, by dictating the composition and the quality of the air we breathe or by controlling the amount of radiation that can penetrate Earth’s atmosphere. Thus, not surprisingly, gas-phase chemistry has been and still is a very active area of research, which has traditionally required the combined effort of chemists, physicists, and biologists. The absence of a solvent allows identifying the intrinsic reactivity of molecules, which often challenges our intuition, which is more prone to consider chemical processes occurring in solution. However, this is compensated by the fact that many experiments performed in the gas phase can be accompanied by accurate quantum chemistry calculations, which are often crucial to identify the basic mechanisms and even to predict phenomena hitherto unobserved in the laboratory. As a consequence, modern stateof-the-art gas-phase experiments are almost always supported by theoretical modeling. This Virtual Special Issue of The Journal of Physical Chemistry A pays tribute to two outstanding figures of theoretical gasphase chemistry, Manuel Yáñez and Otilia Mó, on the occasion of their 70th birthdays. Their scientific careers started in Spain at the beginning of the 1970s, a time when commitment to research in their home country was not easy. Between 1974 and 1975, they obtained their Ph.D. at Universidad Autónoma de Madrid (UAM), by this time a recently created university. From 1974 to 1976, they moved to Carnegie Mellon University in Pittsburgh, Pennsylvania, where they worked in the group of John Pople (Chemistry Nobel Prize 1998), thus getting in © 2018 American Chemical Society
Published: July 5, 2018 5671
DOI: 10.1021/acs.jpca.8b03669 J. Phys. Chem. A 2018, 122, 5671−5672
Special Issue Preface
The Journal of Physical Chemistry A
collaboration with the experimental group of I. Cuadrado at UAM. Manuel and Otilia not only made fundamental scientific discoveries that helped us to understand a variety of gas-phase chemical processes by using the most advanced theoretical tools but also played a key role in boosting quantum chemistry as a research field in Europe and, in particular, in Spain. At the end of the 1990s, they promoted the creation of a common doctorate program in theoretical chemistry and computational chemistry (TCCM) in Spain. Their great enthusiasm and commitment, as well as their visionary character, allowed them to bring together 17 Spanish universities in a common project that became a reality in 1999. They did not stop here. Five years later they launched a master in TCCM involving 42 universities of 8 European countries, a master that has received the maximum distinction in Europe through the Erasmus Mundus Master label. This master is nowadays a reference for theoretical chemistry studies in Europe. More recently, they have extended the original TCCM joint doctorate program developed in the Spanish context to the level of a European Training Network. Their passion in transmitting knowledge to future generations of scientists has certainly left an indelible imprint in several generation of students, at either the undergraduate or the graduate levels, and is an excellent example of their successful accomplishment. We also highlight Otilia’s crucial role in promoting the role of women in science, through her various administrative responsibilities at the national and international levels. Otilia has also been decisive in shaping the development of science in Spain, as for one year she was the head of the Department of scientific projects in the Spanish ministry of Science and Innovation. On a final note, we could not finish this tribute without mentioning that, besides their tireless efforts in producing science at the highest level and ensuring that this science is transmitted to future generations, Manuel and Otilia are also well-known for “other” important achievements that they selflessly shared with their scientific colleagues. Manuel’s “almendrados”, a sort of cookies made of egg-white and almonds, and Otilia’s “donuts” are widely known and highly recognized by their collaborators, including the authors of this tribute. Any special celebration in their lab was always accompanied by these delicacies. In spite of having left their homeland, Galicia, in their early twenties to start a scientific career in Madrid, Manuel and Otilia never lost the links to their origins. On the contrary, wherever they go, they are enthusiastic promoters of this (often forgotten) region in the northwest of Spain. We are sure that we will have many other opportunities to enjoy and learn about these other activities in the years to come. Gas-phase chemistry certainly deserves it!
chalcogenovinylaldehydes HC(X)CHCHCYH or chalcocyclopentadienes. Finally, in the field of atomic collisions, in collaboration with A. Macı ́as and A. Riera, they developed a code to perform fullCI calculations in two-electron systems, including pseudopotentials and model potentials, paving the way to study charge transfer reactions at collision energies of a few keV per amu, or the electronic structure of diatomic quasimolecules. At the same time, Manuel took the first steps toward extending twoelectron computational codes to describe autoionizing states of atoms and molecules by using a Feshbach-type methodology in combination with a simple discretization method. By the end of the 1980s, Manuel and Otilia were already well-known theoretical chemists with well-rooted collaborations that involved leading experimental groups in gas-phase ion chemistry, such as the groups of R. W. Taft at the University of California and F. Cacace in Rome. Yet, it was at the beginning of the 1990s when some of their most fruitful collaborations started. The experimental group of J. L. Abboud at the Spanish Research Council opened the door to investigate the intrinsic reactivity of several families of compounds as lactams, azetidines, or thiocarbonyls and highly strained sytems: cubane, adamantane, tetraphosphacubane, or P4 (in this system they introduced the concept of the planetary system, exemplified by P4Li+, where Li+ orbits around the molecule). They also stated the bond activation-reinforcement (BAR) rule, which predicts that if protonation is produced in the most electronegative atom in a bond, it leads to a weakening of this bond, whereas if protonation occurs in the less electronegative atom it produces a bond reinforcement. This rule was used to theoretically predict dissociative proton attachment in F or Cl derivatives; experiments confirmed that when protonation is produced in a C−F or C−Cl bond, the bond is broken and a stable carbocation is generated in the gas phase. Also during this decade Manuel and Otilia started a collaboration with the experimental groups of J. P. Morizur, J. Tortajada, and J. Y. Salpin in the study of the gas-phase reactivity of biomolecules toward different metal cations. These rich collaborations, still ongoing, have been rewarded with almost 50 publications, in which the nature of the interaction of metals such as Cu+, Cu2+, Ni+, and Ca2+ has been unravelled. Further, the reactivity of systems such as formamide, acetamidine, urea, gycerol, ethylendiamine, amino acids, sugars, or uracil when interacting with metal cations has been investigated. In the last 20 years, they have kept a strong research activity leading to the prediction of new phenomena in chemistry: they have introduced the “scorpion effect” as a way to enhance Li+ basicities of benzyl derivatives. They have explored in collaboration with the experimental group of J. C. Guillemin the properties of new families of compounds such as germanes, stannanes, As and Sb compounds such as vinylarsine and vinylstibine, or boranes, alanes, and gallanes. Also worth mentioning is their seminal work in the definition and characterization of Be compounds establishing a new kind of molecular linkers: the beryllium bond. They have shown that conventional bases such as aniline can be converted by interaction, through beryllium bonds, into acids stronger than most of the known oxyacids as the phosphoric acid, or how beryllium bonds can induce spontaneous ion-pair formation, or the existence of Be derivatives that act as anion sponges. Remarkably, Otilia has also made important contributions in the past few years to the study of ferrocene derivatives, in
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Leticia González Manuel Alcamí Fernando Martín ASSOCIATED CONTENT
S Supporting Information *
The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jpca.8b03669. Table of contents for the Manuel Yáñez and Otilia Mó Festschrift (PDF)
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DOI: 10.1021/acs.jpca.8b03669 J. Phys. Chem. A 2018, 122, 5671−5672
