A Festschrift in honour of Professor Claudio Zannoni

It is our pleasure to open this Festschrift dedicated to our senior colleague Professor Claudio Zannoni on the occasion of his 70th birthday and his retirement after more than 40 years of service as Scholar of Physical Chemistry at the University of Bologna. This special issue collects a rich number of diverse contributions by collaborators, friends and colleagues from all over the world, factually demonstrating not only Claudio’s great achievements in liquid crystal research but also the respect of the community for one of its most distinguished members.

In the following, we take the chance of giving a personal and necessarily imperfect historical glimpse on Claudio’s activity as researcher, mentor, and member of the (inter)national scientific community. We wish it will be found inspiring by those who have not personally known Claudio, an occasion of pleasant memories and recollections for those who have been personally gifted by his insights, and entirely forgivable by Claudio in the circumstances.

Researcher

Claudio started to work on liquid crystals during his graduate studies at Southampton University, under the supervision of Prof. Geoffrey Luckhurst, at that time a freshly appointed reader. This was not planned. Being theoretically inclined, Claudio initially wished to work in quantum mechanics, and when it was time to begin planning for the Master thesis project, he asked the local physical chemistry head, the spectroscopist Prof. Carlo Zauli, to join the theoretical chemistry group. Zauli knew Claudio was a very bright student and thought otherwise, so he told him it would be better if he joined the spectroscopy group instead. Professor Zauli was the kind of leader who would not take no for an answer: after Claudio declined Zauli’s offer, Claudio found himself banned from the Physical Chemistry Department as persona non grata, and eventually exiled to the Organic Chemistry Department where he was welcomed to work on the computational analysis of electron spin resonance (ESR) spectra under the supervision of Prof. Gianfranco Pedulli. During this period, Claudio wrote a programme to simulate ESR spectra that after his graduation kept being used for at least one decade.

Having completed his Master thesis (Figure 1), Claudio accepted Prof. Pedulli’s suggestion to continue his work in Prof. Geoffrey Luckhurst’s lab. So, immediately after receiving the Laurea degree in Industrial Chemistry magna cum laude, in 1972 Claudio set at the wheel of a small FIAT 500 and drove all the way to Southampton with his freshly wed wife Nicoletta. He received his PhD in 1975, defending a thesis On the molecular theories of liquid crystals, which led to the publications of several articles, including one in Nature [1].

Figure 1. (Color Online) Claudio being conferred the master’s degree (‘laurea’) in Industrial Chemistry, Bologna, 1972.

After the PhD, Claudio moved back to Bologna to join the Organic Chemistry Department of the Industrial Chemistry Faculty as Assistant Professor. Soon after he was called by Carlo Zauli himself (i.e. the very professor who banned him first) to the Physical Chemistry Department, where he quickly progressed through the Italian university ranks, becoming Associate Professor (1982) and, since 1987, Full Professor of Physical Chemistry.

As can be surmised from his PhD thesis title, Claudio shaped his scientific career as a theoretician, and most of his research activity was, and it is still, conducted in the field of liquid crystals and anisotropic soft materials by means of a wide range of theoretical, and computational methods. Indeed, aside from computer simulations, Claudio also developed theories and data analysis methodologies for studying and characterising ordered media, including polymers and lipid membranes, using various spectroscopic techniques, like fluorescence depolarisation, ESR, NMR, and dielectric relaxation. In particular, Claudio focussed on the determination of the order parameters and orientational dynamics of solutes (molecular probes) dissolved/dispersed into an anisotropic medium. Just to give a few examples, we mention here the maximum entropy techniques for extracting conformational information on flexible molecules [2–4], the analysis of fluorescence depolarisation data in liquid crystals [5,6], and more in general the theoretical treatment of rotational–translational diffusion for biaxial molecules in uniaxial and biaxial phases [7–12]. Claudio was so keen on putting at test those theories that he also developed an experimental research line within his group, together with Riccardo Tarroni and Alberto Arcioni, to study order and dynamics in various complex anisotropic systems using fluorescence depolarisation measurements [13,14] and ESR based on spin probes [15–17].

Although being very gifted in devising theoretical approaches for interpreting spectroscopical data, Claudio’s biggest scientific love has always been the application of computer simulations to the study of physical properties of mesophases, of which he is probably the most recognised expert worldwide. He pioneered simulations during the PhD years, participating also to some early issues Luckhurst’s famous series of papers Computer simulations of anisotropic systems [18–21], and contributing two chapters to the book The Molecular Physics of Liquid Crystals (1977, the green book for those in the field). In Luckhurst’s group, Claudio started working on anisotropic lattice systems, mainly based on the Lebwhol–Lasher spin model, using Monte Carlo simulations, a fairly novel approach at the time. With the continuous development of computers and their number crunching capabilities, he would later pursue these studies also with two of us (R. B. and L. M.) by means of molecular dynamics simulations [22] and off-lattice (Gay–Berne) [23] and atomistic models [24], to not mention many excellent contributions to the study of materials for organic electronics [25–27], a research field in which he is also well-known and regularly invited to international conferences.

In addition, Claudio never stopped advancing his PhD work on statistical theories of bulk and confined liquid crystals. A quite detailed summary of his computer simulations research in liquid crystals, enriched with personal recollections about these early years, can be found in the perspective written by Claudio for in this very same issue.

Teacher and mentor

Besides being a keen researcher, Claudio has also steered his passion into teaching and has proved to be an excellent maestro initiating hundreds of chemistry students to the beauty of the physics of molecular materials, to the extent of compelling many of them to further pursue studying and researching the topics he initially fascinated them into. Claudio’s wide and deep scientific knowledge, his excellent reputation, and the infectious enthusiasm for Science have also attracted to join his lab many Italian and foreign graduate and postgraduate students (Figures 2–4), and it is a pleasure for us to give voice here to some of their personal recollections and memories, in rigorously random order:

Figure 2. (Color Online) Claudio with collaborators and students in 1988. From the left to the right: Paolo Pasini, Garth Shilstone, Luca Longo, Alberto Arcioni, Fabio Biscarini (graduated that day), Claudio, Cesare Chiccoli.

Figure 3. (Color Online) Claudio’s group in Bologna, 2005. From the left to the right: Luca Muccioli, Matteo Ricci, Adriana Pietropaolo, Giustiniano Tiberio, Maria Beatrice Di Cicco, Silvia Orlandi, Corrado Bacchiocchi, Roberto Berardi, Antonio Pizzirusso, Claudio, Davide Micheletti, Laurence Ellison, Gregor Skačej, Ilaria Vecchi, Ozan Kayacan, Alberto Arcioni.

Figure 4. (Color Online) Claudio’s group in Bologna, 2013. From the left to the right: Claudio, Matteo Ricci, Gabriele D’Avino, Luca Muccioli, Federico Bazzanini, Mattia Felice Palermo, Manuel Vieider, Lara Querciagrossa, Erika Benini, Isabella Miglioli, Roberto Berardi, Silvia Orlandi, Antonio Pizzirusso, Yoann Olivier, Otello Maria Roscioni.

Alberto Arcioni, second master student co–supervised by Claudio in 1979 (after Paolo Pasini), and currently Associate Professor in his group:

I’ve been working with Claudio for almost forty years now, and I have always admired his very deep scientific knowledge, his excellent teaching skills, the great morality and sense duty towards academic institutions, his intellectual integrity and his always proactive and optimistic attitude when facing new scientific challenges.

Lara Querciagrossa, Master thesis student 2008, then graduate and now Research Associate in the group:

Prof. Zannoni is not only an inspirational teacher but also an enthusiastic supervisor. Because of his passion, I moved from experimental to computational chemistry and joined the terrific world of simulations. His expertise, motivation and support make every topic interesting and encourage to work on each project with curiosity and thrill.

Adriana Pietropaolo, graduate student 2004–2007, now Permanent Researcher in Chemistry at the University of Catanzaro:

Everything I know today on molecular simulations, I learned it from Professor Zannoni. His elegant way of writing equations, his passion in teaching and communicating science, make Professor Zannoni a blessing for all of us who had the fortune to have been trained under his supervision.

Angelo Vaccari, college classmate since 1968, and currently academic colleague and Full Professor at the Industrial Chemistry Department:

I know Claudio from the time of the University studies at the Faculty of Industrial Chemistry of Bologna and, notwithstanding two very different characters and, of course, some different opinions, in all these year our friendship and esteem remained fully unchanged, underlining that the human qualities were and are most relevant for both of us.

Riccardo Tarroni PhD student and postdoc 1987–1992, now Professor of Physical Chemistry at the University of Bologna:

I met Claudio for the first time in 1985. I was just a fifth year student and Claudio held a course where he taught the basics of computer science on the PC. The final assignment of the course was to write a small program in BASIC. Maybe I took the assignment too seriously, or most probably I was pushed by Claudio’s enthusiasm, so at the end I wrote my first molecular dynamics code on a 64 KB Apple II PC. In any case, I enjoyed it a lot!

Marco Cecchini, Master thesis student 1999, now Professor of Chemistry at the University of Strasbourg:

I first met with Claudio in 1998 as an undergraduate. His lectures in Physical Chemistry impressed me as I could see for the first time how abstract mathematical tools and computer simulations could be used to describe fascinating physical phenomena at the molecular level. I am grateful to him for introducing me to Science life (i.e. research work, lab meetings, international workshops, etc.) and $\dots$ to pasta con le sarde in the beautiful Erice!

Antonio Pizzirusso master, graduate, and postgraduate student 2005–2013, now Research Associate at the University of Salerno:

I met for the first time Prof. Zannoni as a teacher of Physical Chemistry of Materials during the fourth year of my chemistry courses. At that time, I had already made up my mind to go for an internship in quantum chemistry. However I was so charmed by Claudio’s lectures, that he was delivering with such a great passion and enthusiasm, that I changed my mind and eventually opted for a computer simulation thesis in his group.

Silvia Orlandi, Master thesis student 1994, then graduate, postgraduate, and now Permanent Researcher in Claudio’s group:

From the very beginning I was fascinated by Claudio’s extraordinary ability and passion to communicate science – clearly and engagingly – with everyone, including the under-graduated students as I was at that time. Claudio introduced and supervised me in the captivating world of computer simulations; he always had an enthusiastic comment, an advice, and, on occasion, some criticism, but the criticism was always carefully constructive and positive. I feel very privileged to have known him and to have benefited from his wisdom and knowledge for such a long period.

Corrado Bacchiocchi, graduate and postgraduate student, 1990–1996 and 2000–2009, now Researcher in Chemistry at the University of Camerino:

From the start I was fascinated by the special relationship that Claudio has with computers and programs. In those days he used to read The TeXbook during his train commute between Ravenna and Bologna, and my undergraduate thesis was the first to be typeset in TeX in the Group. Whenever one computer was not behaving as expected, he used to say, with his gentle Ravenna accent: ‘$\dots$ shon dele macchine $\dots$’ (after all $\dots$ they are just machines). And whenever one of us was not getting the expected results, his suggestion was ‘$\dots$ just add a couple of lines of FORTRAN code $\dots$’

Vincenzo Palermo, Master thesis student 1995–1996, now Researcher Director in Chemistry at CNR Bologna:

I remember Claudio striking me already at our very first encounter, explaining me the mathematical power of random numbers. ‘Throwing randomly darts at a geographical map’ – he said – ‘and counting the number of hits in each country, one can calculate the area of the different nations, an impossible task to perform instead with any mathematical equation’. He was of course introducing the Monte Carlo method, based on random displacement of molecular positions and orientations, which I applied to the study of mesogens on graphite during my Laurea thesis with him. After graduating, I left simulations to become an experimentalist (I don’t know if Claudio ever forgave me for this), but still today I am fascinated in seeing how sometimes randomness is stronger than accurate planning.

Giustiniano Tiberio, graduate student 2002–2006, now Technical and Safety Director at Esplodenti Sabino s.r.l.:

I could never forget the period of my life in which I took the decision of joining Claudio’s group for my Master thesis. He immediately charmed me with his passion for science and his extraordinary skills in explaining complex problems by means of simple and understandable concepts. During those years spent in the lab, I learned how to work on long term objectives believing in my ideas, how to recognize and apprehend from my own mistakes, and most importantly I remember the deep satisfaction of obtaining long–awaited results after many efforts. I will always be grateful to Claudio for guiding me through this human and scientific experience.

Gregor Skačej, postdoc 2003–2005, and now Lecturer at Physics Department, University of Ljubljana:

I first met Claudio when I visited Bologna as a PhD student in autumn 1997. During this one-week stay, we have tested a procedure for calculating dynamical NMR spectra of liquid crystal droplets, together with Paolo Pasini and Cesare Chiccoli. This short encounter then evolved into a long-term collaboration that taught me how to perform Monte Carlo simulations myself, rather than just interpreting the simulation output. After more than two decades, our collaboration is still alive, and during all this time I have been repeatedly impressed by Claudio’s deep insight into very diverse fields of science that he has always been able to communicate to others in a soft but firm manner.

Gabriele D’Avino, postgraduate student 2010–2013, now Permanent Researcher in Physics at CNRS Grenoble:

I joined Claudio’s group for my first post-doc period, having the privilege of being plunged into the exciting world of numerical simulations of soft matter in such an excellent environment. I reserve to the period spent in Bologna a special place in my memories, for all I could learn there and the convivial lab moments. I remember the long discussions in Claudio’s office regarding atomistic simulations of the nucleation and growth of molecular crystals from the vapor phase. What we were doing was so pioneering, as actually I would have appreciated only later, that it was quite unclear to all of us how could we quantitatively characterize the results of our simulations, and this turned out in very frank and enriching scientific confrontation on a daily basis.

Andrew Emerson, postdoctoral student 1991 and 1994–1995, now Senior Researcher at CINECA:

I came to work with Claudio because after my PhD, I decided I wanted not only to stay in research but also experience life in another country, Italy being a good option for the usual reasons. Claudio was the obvious choice as host because he had studied with my supervisor in Southampton, Geoffrey Luckhurst, who encouraged me to continue my studies with one of the brightest scientists in Europe. So I moved to Bologna and spent a very happy year, inspired by a researcher full of ideas and enthusiasm. At the end of the grant, I had to go back to the UK, but with Claudio’s help I managed to return to Bologna three years later and continue working with him and his group for another couple of years. Twenty years on I find myself still living in Bologna, happily married and with a young son of whom I am very proud. I don’t think it is an overstatement to say that Claudio has been an important influence in my life and I am extremely grateful to him.

Francesco Spinozzi, Master thesis student in 1989, then PhD in 1994, and now Associate Professor at the Università Politecnica delle Marche, Ancona:

I first met Claudio while attending my Master Degree courses at the University of Bologna. He was that kind of teacher able to spontaneously attract students. With him, Physics, Chemistry and Mathematics were a unique blend capable to intrigue our mind and generate the most precious thing: the passion for science. The willingness to contribute to a fantastic adventure. The passion for complexity tackled with two tools: human mind and computer. Claudio always explained things, also the most complicated and fundamental ones, by showing what could be the next step to advance knowledge about it; offering you, in some way, the possibility to make your own steps forward towards such endeavour. In short, he has been a person that has opened ways to the world of academic research. And now, some thirty years after, I certainly feel that I am where I am thanks to Claudio. Without him, without his suggestions and support in the most difficult and delicate times, I possibly would not have gone on. Especially after the completion of one’s own PhD – when you know who you are, but you do not know where you could go – he taught me to be confident of my inclinations, to follow any opportunity to go on with my research, independently on the economic conditions or on the country offering the possibility for such pursuit. Claudio will never be retired.

Fabio Biscarini, Master student 1985, now Full Professor of Chemistry at the University of Modena and Reggio Emilia, Italy:

I was the first Laurea student in Industrial Chemistry fully supervised by Claudio (Figure 2), working for my thesis internship from 1985 till 1986. I also spent further 8 months in 1988 with Claudio, after I returned back from the National Service before leaving for graduate school in the USA. I chose Claudio as my thesis advisor because I was interested in theory, and I was completely charmed by his lectures on statistical mechanics of liquid crystals. In particular, I was impressed by how natural he was in handling closure of the Wigner’s matrices. For me, a young theorist–wanna–be, it reminded me of a Maestro going through the writing of a score of an opera, with a light sign and his beautiful calligraphy. I believe the aesthetics of science Claudio transmitted in his lectures, was a first important factor to be passionate about science. Then I remember clearly my first day as an internship student: Claudio simply told me ‘the switch of the VAX terminal is on the rear’, and I think I spent the whole day, maybe more, trying to understand what to do afterwards $\dots$ I recognize he has been a great mentor, as he drove me, a young inexperienced student, to work on a frontier problem (at that time) of liquid crystal modelling that has lead us to produce four papers out of a Laurea thesis. This experience has been a milestone in my career, and I am sincerely grateful to him since then. I always try to imitate him with my students, but I recognize that I am not always as good as him. What I suppose Claudio teaching has been to me, in the sense that I took it with me throughout these years, is the hard working attitude and discipline in science that is requested to be a scientist. When I look back, I see this as a very important heritage he has transmitted with his example, and that I have been also trying to convey to my own students. I was also fortunate to keep always an excellent personal and a scientific relation with Claudio, even when I grew into an independent scientist and later professor. We supervised Vincenzo Palermo together, and were partners in exciting European collaborative projects. So we had the chance to discuss science from our different perspectives then. In this manner I realized that, no matter how experienced and independent I have become, Claudio is still my Maestro. Auguri Claudio con tutto il cuore e gratitudine!

The last recollection we would like to report is by Roberto Berardi, Master thesis student in 1988, then PhD in 1992, odd-years postdoc, and now associate professor in Claudio’s group, and one of the authors of this preface:

It started this way: one morning of the first autumn term of my freshman year (1983) our bossing math professor could notcome to class (hurray!). His lecture was eventually given by a young lad in his 30ies who was speaking a different language with plenty of never heard before jargon like quadratic forms, linear transformations, rotation matrices and other interesting math he claimed you could experiment with by using a computer, and a few lines of BASIC (actually, always five, whatever the algorithm was – he was clearly ahead of his time and he was already thinking in Python). None of us fully understood what he was talking about (and, more importantly, what his name was), but the magic word had been pronounced: computer. I was really excited (and still I am) about the possibility of using computing machines to solve scientific problems, and the appearance of this lad (you correctly guessed it was Claudio) was an unexpected invitation to a misterious and fascinating world I wanted to explore. Unfortunately, the lad was nowhere to be found, and not knowing his name did not help. Some uneventful weeks passed marked by no noteworthy daily lecture/lab/study routine, until one day by sheer chance I crossed him in a corridor. It was a matter of few seconds to stop him by, introduce myself, and find myself being informally invited to drop into his ‘lab’ (actually a narrow corridor with computers seated on top of an old laboratory bench) for using an APPLE IIe. Real computing people (with Riccardo Tarroni and Fabio Biscarini among them) were using the nearby TTY terminal connected to a much more powerful VAX 780 located a couple of floors below in alien grounds, so the APPLE IIe computer was idle most of the time and fully available to me, and I could talk with the students there, especially Fabio and Luca Longo. So, I started fiddling with silly BASIC programs, and a few years afterwards, when the time came, I simply shifted place a metre to the right in front of the VAX terminal to do more interesting scientific programming in FORTRAN 77 (no Python yet) for the maximum analysis of NMR data to study the conformation distribution of simple flexible molecules. In a year time Francesco Spinozzi would join the lab and we formed the core of the maximum entropy research; also Fabio was frequently visiting Claudio, arriving in full military fatigues and combat boots. After my turn of National Service I came back to Claudio’s lab as a graduate student and I was greeted by Andrew Emerson who together with Claudio initiated me to the computer simulations of Gay–Berne models.

Since that unexpected lecture Claudio has always being true to the role of being an inspirational guide into research–land. To this days, no matter what is the subject, when you talk to Claudio you always feel he is still there ahead, waiting for you a few paces in front, seeing things you still have to notice and leading the way.

However, this is not the end of the story. After my master graduation my parents bought a house in the mountain village my mother was born. After moving there they got a cat who was regularly exploring not only the surrounding woods but also the nearby houses. One afternoon I was talking with my mother about these feline habits when she told me: ‘Do you know that the garden she likes more is that of old mill down to the river which belongs to a professor of Bologna University?’ – ‘I didn’t, who is he? What’s his name?’ – ‘Well, I can’t tell; I don’t know him personally and people always refer to him using a nickname I forgot.’ Imagine what a surprise it was when I found out the mysterious professor to be Gianfranco Pedulli, the former supervisor of my supervisor. The perfect conclusion to this unexpected sequence of connections (and supervisors) arrived a few years afterwards when Claudio’s PhD supervisor, Prof. Geoffrey Luckhurst, who had recently visited his friend Prof. Pedulli, addressed me with an unexpected question: ‘I saw your house! How many palm trees have grown in the frontyard?’ – ‘Ehm, I never counted them, I think three’ – ‘No you are wrong, there are four of them, one still very small’. You can always learn from the masters, no matter what.

In the scientific community

Besides being dedicated to research and teaching, Claudio has always believed in the importance of participating and animating the national and international LC community. At the end of 70s, liquid crystals research started to become quite popular also in Italy and Claudio, together with some other young researchers like as Roberto Bartolino, Francesco Simoni, Giancarlo Galli, Giuseppe Chidichimo, Sandro Faetti, Pier Luigi Nordio, Marco Fontana, Franco Rustichelli, Carlo Alberto Veracini, and others, founded Gruppo Nazionale Cristalli Liquidi, the first nucleus of Italian scientists from which the Italian Liquid Crystal Society finally arose in 1994. He was since then always active in a number of Italian and international committees and panels, including, among others, the editorial board of several scientific journals, and supercomputing initiatives such as DEISA and PRACE. The coronation of this body of activities was probably the election of Claudio as Chairman of the International Liquid crystal Society, a role that he covered from 2012 to 2016.

Moreover, to spread and increase the knowledge of the Liquid Crystal science, he founded, together with one of us (P.P.), the International School of Liquid Crystals at the Ettore Majorana Centre for Scientific Culture in Erice (Sicily). This International School started in 1998 on the occasion of a NATO Advanced Study Institute on Computer Simulations of Liquid Crystals and has continued its activity holding courses, workshops and schools at least one per year, reaching the total number of 25 events so far. The latest, held from 7 to 10 October 2018, was a workshop entitled A Scientific Journey in the World of Liquid Crystals and Beyond to celebrate the Claudio Zannoni’s 70th Birthday. The workshop has brought together many colleagues, collaborators and friends who have presented their recent works (Figure 5). We are happy and honoured to have contributed to this workshop, with the invaluable help and support of our colleagues and friends Alberto Arcioni, Cesare Chiccoli, and Silvia Orlandi. We think that the workshop and this special issue do not mark the conclusion of a brilliant scientific career, but are instead a stepping stone from which we wish Claudio to continue with new ideas and a renewed enthusiasm for research.

Figure 5. (Color Online) Group picture of the participants to the workshop held to celebrate Claudio’s 70th birthday, A Scientific Journey in the World of Liquid Crystals and Beyond, in front of San Domenico Monastery, now the Patrick M. S. Blackett Institute. Erice, Italy, 8 October 2018.

Finally, we would like to thank all the authors contributing to this exciting special issue, Taylor & Francis for making it possible and for financial support of the Erice workshop, and the editor in chief of Liquid Crystals, Prof. Corrie T. Imrie, for his precious suggestions and invaluable editorial help.

Bologna, 22 October 2018.

Disclosure statement

No potential conflict of interest was reported by the authors.