Trying to Understand, Making Bonds

Author(s):  
Roald Hoffmann

In 2007, on the occasion of my 70th birthday, Bassam Shakhashiri organized a symposium for me at the Boston meeting of the American Chemical Society. The session was entitled “Roald Hoffmann at 70: A Craftsman of Understanding.” I began my talk with thanks to many. That section has been shifted to the end of this chapter. I was born in a happy young Jewish family in unlucky times, 1937. In that war, most of us perished, 3800 of the 4000 Jews of Złoczów, now Zolochiv in Ukraine. Among those who were killed were my father, three of four grandparents, three aunts, and so on. I just want to show you three photos which relate to that time, one old and two recent. The last 15 months of the war we were hidden by a good Ukrainian man–Mikola Dyuk, the schoolteacher in the small village of Univ. The first year we were in an attic of the schoolhouse, the second year in a storeroom with no windows, maybe 6 x 10 feet, on the ground floor. Here are two photos from 2006, when my sister, my son, and I visited Univ. Here is the attic in which we were hidden, with its one window. The storeroom, a passageway, another ground floor room are gone, rebuilt into a new classroom of Univ’s school. It’s a chemistry classroom. Such is fate. Under the plank floor we dug a bunker to sit in if the police came to the house. I was five and a half when we went in. And nearly seven when we went out. Here’s a photo of me, a few months after we came out. We survived. Some of us. Good people helped us, I tell their story. I am also the speaker for the dead—the three million Polish Jews who were killed do not have good stories to tell, or photos to show. We built a new life, in refugee camps where I read of Marie Curie and George Washington Carver, and then came to America in 1949.

2020 ◽  
Author(s):  
MAK Williams ◽  
V Cornuault ◽  
AH Irani ◽  
VV Symonds ◽  
J Malmström ◽  
...  

© 2020 American Chemical Society. Evidence is presented that the polysaccharide rhamnogalacturonan I (RGI) can be biosynthesized in remarkably organized branched configurations and surprisingly long versions and can self-assemble into a plethora of structures. AFM imaging has been applied to study the outer mucilage obtained from wild-type (WT) and mutant (bxl1-3 and cesa5-1) Arabidopsis thaliana seeds. For WT mucilage, ordered, multichain structures of the polysaccharide RGI were observed, with a helical twist visible in favorable circumstances. Molecular dynamics (MD) simulations demonstrated the stability of several possible multichain complexes and the possibility of twisted fibril formation. For bxl1-3 seeds, the imaged polymers clearly showed the presence of side chains. These were surprisingly regular and well organized with an average length of ∼100 nm and a spacing of ∼50 nm. The heights of the side chains imaged were suggestive of single polysaccharide chains, while the backbone was on average 4 times this height and showed regular height variations along its length consistent with models of multichain fibrils examined in MD. Finally, in mucilage extracts from cesa5-1 seeds, a minor population of chains in excess of 30 μm long was observed.


2020 ◽  
Vol 27 (35) ◽  
pp. 5970-6014 ◽  
Author(s):  
Md. Jawaid Akhtar ◽  
Mohammad Shahar Yar ◽  
Vinod Kumar Sharma ◽  
Ahsan Ahmed Khan ◽  
Zulphikar Ali ◽  
...  

This review presents the detailed account of factors leading to cancer and design strategy for the synthesis of benzimidazole derivatives as anticancer agents. The recent survey for cancer treatment in Cancer facts and figures 2017 American Chemical Society has shown progressive development in fighting cancer. Researchers all over the world in both developed and developing countries are in a continuous effort to tackle this serious concern. Benzimidazole and its derivatives showed a broad range of biological activities due to their resemblance with naturally occurring nitrogenous base i.e. purine. The review discussed benzimidazole derivatives showing anticancer properties through a different mechanism viz. intercalation, alkylating agents, topoisomerases, DHFR enzymes, and tubulin inhibitors. Benzimidazole derivatives act through a different mechanism and the substituents reported from the earlier and recent research articles are prerequisites for the synthesis of targeted based benzimidazole derivatives as anticancer agents. The review focuses on an easy comparison of the substituent essential for potency and selectivity through SAR presented in figures. This will further provide a better outlook or fulfills the challenges faced in the development of novel benzimidazole derivatives as anticancer.


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