Editor’s Introduction

This is an important year for crystallographers, with the IUCr International Congress in Calgary, Canada. The IUCr Congress takes place every three years, in a different country each time. I have been fortunate to attend almost every one since the Moscow meeting in 1966, and it has always been the most important event for me as a place to meet other crystallographers and friends and to make new contacts.

The Congress typically attracts 1500-2500 participants and features a wide variety of microsymposia, lectures, and social events. The real importance of the Congress, it seems to me, is that, despite all the international troubles in the world right now (and I am sorry to say, there are many), this is a special opportunity for us all to meet, irrespective of the current threats. It is worth recalling that the IUCr itself was born of the ravages of the Second World War, with the intention of unifying all of us with a common interest in Crystallography that superseded national boundaries and confrontations. In a sense, it is a kind of “United Nations” devoted to peaceful coexistence. If you are a crystallographer or someone interested in crystallography, I strongly recommend attending the Congress. This year, it will be held in a splendid location and is expected to be open to participants from all nations, regardless of political divides. I expect to be there, and I shall be touting for new articles for the Newsletter.

Readers of the IUCr Newsletter will have noticed that last year we changed from publishing four issues per year to six issues. Initially, I was worried we wouldn't have enough interesting material if we spread content across so many issues. However, I need not have worried, as it seems that we never found ourselves with too little material. In 2025, we published 132 articles, compared with 99 in 2024. Among these were 16 obituaries, 19 meeting reports, 15 feature articles, and many commentaries on various topics. Much is due to the hard work of the IUCr staff, especially the Head of IUCr Marketing, Kezia Bowman and her assistants. If you attend the Congress, make sure you visit the IUCr stand and meet the people who work so hard on our behalf.

In this issue, we have several articles that I think should interest you. I single out just a few here. For instance, Istvan Hargittai writes about his interview with Nobel Laureate Aaron Klug, renowned for his pioneering work on viral structures using electron microscopy. Aaron died in 2018 (see obituary), and Istvan’s article celebrates 100 years since his birth. You can read about his history and achievements, plus Aaron’s words recorded in the interview.

Another article is by Ilia Guzei, who discusses postage stamps issued in Pakistan illustrating the discovery of X-rays by Rӧntgen. It is interesting to see the scene of Rӧntgen’s laboratory. I think it is worth it at this point to reread the article, published a few years ago in the Newsletter, about the Ukrainian-born physicist Johan (Ivan) Puluj, who invented a special lamp that, unknowingly, produced X-rays a few years before Rӧntgen’s discovery. It seems that both knew each other.

Natalia Dubrovinskaia writes about an important monograph published in February 1911, 115 years ago, before the discovery of X-ray diffraction (for the record, the first experiments demonstrating X-ray diffraction were conducted by Friedrich and Knipping in April of that year). This was on diamond (Der Diamant) by Alexander Evgenjevich von Fersmann and Viktor Mordechai Goldschmidt and dealt with the morphologies exhibited by diamond crystals coming from many localities.

The various crystallographic databases are vital as useful compilations of crystal structures determined by crystallographers over many years. This is where one goes to download relevant structural information. However, there is much evidence of duplicate crystal structure data in the databases. This is discussed by Natalie Johnson, Ian Bruno, Seth Wiggin, and Matt Lightfoot, who argue that duplication may be acceptable in many cases.

There are many special commissions supported by the IUCr. One of them is the Nomenclature Commission. Now this may seem rather dry at first glance, but it is actually one of the really important commissions, for this is where knowledgeable crystallographers discuss together such matters as scientific definitions and notation that we all use in our own publications. Getting these correct is important for scientific communication. Unfortunately, many of our scientific colleagues seem unaware of this and consistently use incorrect terminology when discussing anything related to crystallography, which only spreads confusion. For example, take a look at the article by Massimo Nespolo. Recently, the Nomenclature Commission held a long discussion about how to refer to the number of formula units in a unit cell. The question, briefly, was: Can this number be fractional? You can read about the results of the discussion written by Carol Brock.

Looking back to the IUCr Congress of 2023 in Melbourne it will be recalled that a huge model of the structure of diamond was on display. Stuart Batten and others describe what they did with all the bits left over from the Congress. Model kits were created and sent to primary schools free of charge all over Australia and New Zealand. This is an excellent example of outreach.