PHOTON III – Mixed Mode Detection 2 Active Area 140 x 200 mm 2 Active Area 140 x 100 mm 2 Active Area 100 x 70 mm „We cannot solve our problems with the same thinking we used when we created them.“ Albert Einstein PHOTON III – Best performance for your application needs The PHOTON III detector series is available in three different sizes and introduces mixed-mode photon counting to dramatically improve performance: No parallax smearing for superior data Photon counting with zero read noise and zero dark current for the ultimate in sensitivity No count rate saturation for accurate strong signals Dead time free, shutterless and continuous data collection for the fastest experiments www.bruker.com/photon3 Crystallography Innovation with Integrity PHOTON III_IMSD A4 2020-03-10.indd 2 24.03.2020 14:13:19 ACA – Structure Matters www.AmerCrystalAssn.org Table of Contents Index of Advertisers ........................................................1 President’s Column .........................................................2 Remembrances of Larry Dahl .........................................5 ACA Summer Meeting Information .............................. 10 2020 U.S. Crystal Growing Competition ........................ 14 ACA Living History Project - Update .............................. 18 Book Reviews ............................................................... 20 Judy Flippen Anderson Memorial Poster Prize ............... 21 About the Cover: 2021Warren Award: Jacqueline M. Cole Spotlight on Stamps ..................................................... 22 A time sequence of eight crystal structures of the complex, Puzzle Corner ................................................................ 23 [Ru(SO2)(NH3)4(3-methylpyridine)]tosylate2 as its dark-state S-bound SO2 ligand progressively photoisomerizes as a function Corporate Sponsor News .............................................. 25 of t seconds of 505 nm light from t = 0 – 120 s. The heaviest element of the light-induced O-bound OSO photoisomer ACA Financial Statement .............................................. 30 (sulfur) can already be refined after 5 s of light exposure. The anisotropic displacement parameter (ADP) of the carbon atom Corporate Sponsor Members ........................................ 31 in the methyl substituent (Me) of the 3-methylpyridine ligand also starts to become more elongated at t = 5 s, which exhibits libration and this continues to grow throughout this entire time sequence (see small circled highlights). Me librates in the direction that points into the center of the arene ring of the ring rotor, within the periodic framework of the crystal lattice (the trajectory lies perpendicular to the page, as shown by the Index of Advertisers head (+) and tail (X) ends of an arrow). By t = 10 s, this arene ring has started to rotate as a consequence of this interaction Bruker Inside Front with Me as well as its proximity to the protruding oxygen of the eta1-OSO photoisomer, enough of which has now formed Proto 3 that it can be distinguished and refined crystallographically Dectris 4 (see large circled highlights). The plot in the bottom right panel Thermo 7 shows that the photoconversion levels of the rotated ring and CCDC 9 both photoisomers (a small amount of a side-bound (OS)O ATPS 9 photoisomer is also refined) continue to grow with time, while that of the dark-state S-bound SO2 configuration decreases. The R i g a k u 1 6 graphic was created by J. M. Cole wherein all structures were visualized using the crystallographic software, OLEX2. Contributions to ACA RefleXions may be sent to Editor: Please address matters pertaining to advertisements, Paul Swepston............................................paulswepston@me.com membership inquiries, or use of the ACA mailing list to: Kristin Stevens, Executive Director of the ACA American Crystallographic Association Cover: Paul Swepston Book Reviews: Joseph Ferrara P. O. Box 96, Ellicott Station Historian: Virginia Pett News & Awards: Kay Onan Buffalo, NY 14205 Photographer: Richard Bromund Puzzle Corner: Frank Fronczek tel: 716-898-8692; fax: 716-898-8695 Copy Editor: Sue Byram Spotlight on Stamps: Daniel Rabinovich [email protected] Deadlines for contributions toACA RefleXions are: February 1 (Spring), May 1 (Summer), August 1 (Fall), and November 1 (Winter) ACA RefleXions (ISSN 1058-9945) Number 2, 2021. Published four times per year in the spring, summer, fall, and winter for the membership of the American Crystallographic Association, P. O. Box 96, Ellicott Station, Buffalo, NY 14205-0096. Membership in the ACA includes a non-deductible charge of $1.75 from membership dues to be applied to a subscription to ACA RefleXions. Periodicals postage paid at Buffalo, New York. POSTMASTER: Send address changes to ACA, P. O.Box 96, Ellicott Station, Buffalo, NY, 14205-0096. 1 ACA President’s Column Summer 2021 Structure Matters vaccine side-effects. The W.H.O. has identified President’s Column ‘vaccine hesitancy’ as one of the most serious Summer 2021 present global health threats. Professional scientists of all stripes can no longer sit within the ivory tower, but have the responsibility of providing effective, reliable communication to the public and policy-makers. In our discipline of Structural Science, we, of David Rose course, need to continue to build the foundations ACA President of new frontiers. Progress is already underway in understanding the drivers of mutations leading Despite a stubborn third wave of Covid-19 in to variants of the virus. Molecular studies are Ontario, with closed schools and businesses once deciphering how such mutations are leading to again, we cannot help but be optimistic. Vaccines higher infectivity and virulence. As vaccinology are starting to make inroads in many parts of the evolves, structural studies in materials and world, including the US and UK, and, while Canada nanotechnology will lead to more practical, less is lagging behind, progress is accelerating. It expensive, and higher stability products. Structural is time to start looking ahead to make sure the Biology is contributing to vaccines with higher momentum in Structural Science and other areas cross-reactivity against coronaviruses and other of research is maintained. We know that the next pathogens. New approaches to broad-spectrum pandemic is just around the corner. antiviral pharmaceuticals are already underway, including intriguing approaches to host-based There are several lessons that I am taking away therapies, where the host mechanisms that are from this experience. One is how evident it is that critical for infection can be regulated. These we are one global population. In the final weeks approaches rely on structures of molecules of all of 2019, we saw how quickly an infectious agent sizes. Underpinning all these is that none of these can spread throughout the world, despite early rapid advances would have been possible without warning signs; such signs cannot be ignored again. decades of fundamental, discovery research; the We saw how decades of foundational research in importance of continuing strong discovery research Structural and other sciences was able to pay off at the beginning of the innovation pipeline must be in the remarkably quick development of vaccines. appreciated and celebrated. We also learned as the vaccines rolled out, the importance of broad, international distribution; Perhaps most exciting are the implications that the regionalization and hoarding of doses is these new areas will have on other, equally likely one factor contributing to the evolution and devastating health problems. Cancer vaccine spread of variants, prolonging the pandemic in studies are getting a boost from all we are learning all parts of the world. One sociological area that from the pandemic. Studies of pathogenesis and deserves intense study is how the anti-vax and infection will surely be relevant to the serious and anti-science industries have been so successful growing antibiotic multidrug resistance problem. in their communication effectiveness, more so, Even climate change has taken on a whole new even, than fact-based sources. Such movements importance as we understand its impact on wildlife will surely delay the recovery around the world and human population migration, urbanization and and effective counter-approaches will be critical in cross-species transmission of pathogens. limiting the severity of future pandemics. Similarly, the communications industry has not helped, by Finally, perhaps most exciting from the point of sensationalizing and exaggerating incredibly rare 2 ACA President’s Column Summer 2021 Structure Matters view of our Society, is the convergence of critical contributions from all aspects of Structural Science on the pandemic response. Though largely immersed in Structural Biology and Chemistry for my career, I have become even more sensitized to how important areas such as materials, nano- and micro-particles, computational science and others are in coming together to address major global issues. Where would we be without the technical developments of our commercial partners bringing new, more powerful capabilities into our laboratories? I invite you to continue with me on this exciting journey of the contributions of Structural Science to making our world safer and addressing new global challenges. Our embracing the convergence of all aspects of Structural Science within the ACA AXRD family can only accelerate that impact. POWDER DIFFRACTOMETER David Rose 3