scholarly journals A Crystalline Tri-thorium Cluster: When Metal σ-Aromaticity Just Isn’t Enough

2021 ◽  
Author(s):  
Dariusz Szczepanik
Keyword(s):  
Raman Spectrum ◽  
Thermodynamic Stability ◽  
Periodic Table ◽  
Aromatic Rings ◽  
Successful Isolation ◽  
Experimental Raman Spectrum ◽  
Vital Factor ◽  
Aromatic Stabilization ◽  
Charge Shift

Very recently, Liddle and coworkers extended the range of aromaticity to a record seventh row of the periodic table by successful isolation of the crystalline actinide cluster 3 containing at its heart the σ-aromatic tri-thorium ring. In this study we prove that the authors have misinterpreted the experimental Raman spectrum of 3, which eventually led to the wrong conclusions about the role of the σ-aromatic tri-thorium bonding in the synthesized cluster. We demonstrate that the thorium-thorium bond in 3 is not very different from the already known extremely weak actinide-actinide bonds, and the marginal σ-aromatic stabilization in the Th3 ring makes it hardly distinguishable from ordinary non-aromatic rings. Also, we show that the multicenter charge-shift bonding in the Th3Cl6 cage is a vital factor that determines the uniqueness and remarkable thermodynamic stability of 3. By clarifying the misleading conclusions of the original Nature paper and drawing special attention to the essential stabilizing role of actinide-halogen charge-shift bonding, this study may have broader implications for understanding the chemistry of actinides and future attempts to design and synthesize new stable actinide complexes.

scholarly journals IUPAC Periodic Table Challenge

2020 ◽  
Vol 42 (2) ◽  
pp. 18-21
Author(s):  
Juris Meija ◽  
Javier Garcia-Martinez ◽  
Jan Apotheker
Keyword(s):  
General Public ◽  
Periodic Table ◽  
Chemical Elements ◽  
Global Competition ◽  
Daily Lives ◽  
The World

AbstractIn 2019, the world celebrated the International Year of the Periodic Table of Chemical Elements (IYPT2019) and the IUPAC centenary. This happy coincidence offered a unique opportunity to reflect on the value and work that is carried out by IUPAC in a range of activities, including chemistry awareness, appreciation, and education. Although IUPAC curates the Periodic Table and oversees regular additions and changes, this icon of science belongs to the world. With this in mind, we wanted to create an opportunity for students and the general public to participate in this global celebration. The objective was to create an online global competition centered on the Periodic Table and IUPAC to raise awareness of the importance of chemistry in our daily lives, the richness of the chemical elements, and the key role of IUPAC in promoting chemistry worldwide. The Periodic Table Challenge was the result of this effort.

scholarly journals π-Stacking Stopper-Macrocycle Stabilized Dynamically Interlocked [2]Rotaxanes

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4704
Author(s):  
Sing-Ming Chan ◽  
Fung-Kit Tang ◽  
Ching-Yau Lam ◽  
Chak-Shing Kwan ◽  
Sam C. K. Hau ◽  
...  
Keyword(s):  
Crystal Structures ◽  
Thermodynamic Stability ◽  
Combinatorial Library ◽  
Aromatic Rings ◽  
Interlocked Molecules ◽  
X Ray ◽  
Π Stacking ◽  
Dynamic Combinatorial Library

The synthesis of mechanically interlocked molecules is valuable due to their unique topologies. With π-stacking intercomponent interaction, e.g., phenanthroline and anthracene, novel [2]rotaxanes have been synthesized by dynamic imine clipping reaction. Their X-ray crystal structures indicate the π-stackings between the anthracene moiety (stopper) on the thread and the (hetero)aromatic rings at the macrocycle of the rotaxanes. Moreover, the length of glycol chains affects the extra π-stacking intercomponent interactions between the phenyl groups and the dimethoxy phenyl groups on the thread. Dynamic combinatorial library has shown at best 84% distribution of anthracene-threaded phenanthroline-based rotaxane, coinciding with the crystallography in that the additional π-stacking intercomponent interactions could increase the thermodynamic stability and selectivity of the rotaxanes.

scholarly journals Role of the periodic table in discovery of new elements

2011 ◽  
Vol 1 (1) ◽  
pp. 1-5 ◽  
Author(s):  
D.C. Hoffman
Keyword(s):  
Periodic Table ◽  
Predictive Power ◽  
Chemical Elements ◽  
Chemical Properties ◽  
Negative Effects ◽  
Current Form ◽  
Future Role ◽  
History Of ◽  
Chemical Techniques

AbstractThis year (2009) marks the 140th Anniversary of Mendeleev's original 1869 periodic table of the elements based on atomic weights. It also marks the 175th anniversary of his birth in Tolbosk, Siberia. The history of the development of periodic tables of the chemical elements is briefly reviewed beginning with the presentation by Dmitri Mendeleev and his associate Nikolai Menshutkin of their original 1869 table based on atomic weights. The value, as well as the sometimes negative effects, of periodic tables in guiding the discovery of new elements based on their predicted chemical properties is assessed. It is noteworthy that the element with Z=101 (mendelevium) was identified in 1955 using chemical techniques. The discoverers proposed the name mendelevium to honor the predictive power of the Mendeleev Periodic Table. Mendelevium still remains the heaviest element to have been identified first by chemical rather than nuclear or physical techniques. The question concerning whether there will be a future role for the current form of the periodic table in predicting chemical properties and aid in the identification of elements beyond those currently known is considered.

scholarly journals HUMANITY AND HAPPINESS - A VITAL FACTOR IN THE INDEPENDENT LIFE OF THE YOUNG GENERATION

2020 ◽  
pp. 252-255
Author(s):  
Yuldashev Farrux Abdurakhmanovich
Keyword(s):  
Young People ◽  
Key Words ◽  
Young Generation ◽  
Scientific Heritage ◽  
National Values ◽  
Independent Life ◽  
Spiritual Legacy ◽  
Independent Thinking ◽  
Vital Factor

The role of humanism and national values are important in the contemporary policy of Uzbekistan. This study discusses the role and place of the ideas of humanism and tolerance in the development of ethics, culture, humanistic qualities of young people who are the leading forces of our society. The ideas on the wide use of the scientific heritage of the scientists and thinkers in the life of youth and nation have been considered. In the result of the study the factors of nurturing the young generation in promoting harmony and humanism have been drawn. KEY WORDS: stability, independent thinking, personality, society, humanism, worldview, tolerance, progress, spiritual and moral maturity, interethnic harmony, compromise, dedication, diligence, thinker, spiritual legacy.

A role of disordered domains in regulating protein oligomerization and stability

2014 ◽  
Vol 50 (74) ◽  
pp. 10797-10800 ◽  
Author(s):  
Ofrah Faust ◽  
Lavi Bigman ◽  
Assaf Friedler
Keyword(s):  
Thermodynamic Stability ◽  
Protein Oligomerization ◽  
Oligomeric State ◽  
Intrinsically Disordered ◽  
Intrinsically Disordered Regions ◽  
Disordered Regions

This work describes a new role of intrinsically disordered regions in regulating the oligomeric state and thermodynamic stability of proteins.

HYPOTHESIS ON THE SYNERGISM OF RADIATION AND WATER FILTERS IN THE FORMATION OF BIOOBJECTS

2019 ◽  
Vol 21 (1) ◽  
pp. 53-58
Author(s):  
B.L. Oksengendler ◽  
S.E. Maksimov ◽  
S.U. Norbaev ◽  
L.Yu. Akopyan ◽  
M.V. Konoplyova ◽  
...  
Keyword(s):  
Periodic Table ◽  
Chemical Elements ◽  
Electron Shell ◽  
Living Matter ◽  
Heavy Atoms ◽  
The Third ◽  
Water Filters ◽  
Selection Of ◽  
Electron Shells

The article contains a hypothesis on the dominance of chemical elements of top periods of the Periodic Table in living matter. The idea is that the elements of the third and next periods of the table, in contrast to the first two periods, have larger number of subvalent electron shells. Because of this, ionization of the k-electron shell by radiation (kosmic and terrestrial) in the heavy atoms always leads to the Auger cascade, which causes the destruction of molecular chains. This mechanism can play a role of the radiation filter in the selection of light chemical elements in living matter in addition to the mechanism of hydrolytic filter (G.R. Ivanitskii).

Substance and Function

2020 ◽  
pp. 188-203
Author(s):  
Jean-Pierre Llored
Keyword(s):  
Quantum Chemistry ◽  
Philosophy Of Science ◽  
Periodic Table ◽  
Functional Role ◽  
Functional Approach ◽  
Different Types ◽  
And Function

This paper aims to analyze the two aspects of elements, material and conceptual, in order to further understand the functional role played by elements in chemistry. First, we will refer to how Mendeleev gradually built his periodic table. Second, we will both highlight and reflect upon the functional role of elements in chemistry. In doing so, we will refer in particular to Cassirer’s philosophy of science. In conclusion, we propose that a functional approach is important for understanding current chemical practice, especially in nanochemistry and quantum chemistry. This approach also contributes to the analysis of different types of mereology that coexist in chemistry today.

Thermodynamic Stability of Ice II and Its Hydrogen-Disordered Counterpart: Role of Zero-Point Energy

2015 ◽  
Vol 120 (8) ◽  
pp. 1843-1848 ◽  
Author(s):  
Tatsuya Nakamura ◽  
Masakazu Matsumoto ◽  
Takuma Yagasaki ◽  
Hideki Tanaka
Keyword(s):  
Thermodynamic Stability ◽  
Zero Point ◽  
Zero Point Energy ◽  
Point Energy

scholarly journals The central role of the d-block metals in the periodic table

2019 ◽  
Vol 48 (26) ◽  
pp. 9405-9407 ◽  
Author(s):  
Catherine E. Housecroft ◽  
Christine M. Thomas ◽  
Mi Hee Lim
Keyword(s):  
Periodic Table

Welcome to this themed issue of Dalton Transactions entitled “The central role of the d-block metals in the periodic table”

scholarly journals Elements of Sports: From IYPT 2019 to Tokyo 20201

2020 ◽  
Vol 42 (1) ◽  
pp. 5-7
Author(s):  
Miki Hasegawa ◽  
Masamichi Yamanaka ◽  
Osamu Miyamae ◽  
Hayanon Science Manga Studio
Keyword(s):  
Coordination Chemistry ◽  
Chemical Reactions ◽  
Periodic Table ◽  
High Demand ◽  
High Performing ◽  
Human Culture ◽  
The Future ◽  
Paralympic Games

AbstractSports, one of the symbols of the global human culture and a unit of peaceful society, excite both competitors and audiences. During the game and even practice, athletes concentrate to choose not only a comfortable design but also high-performing materials of their shoes, rackets, uniforms, etc. Under the high demand of athletes, sports materials are evolving with the support of new chemical reactions and coordination chemistry. Here, we exhibit the role of elements in sports. The International Year of the Periodic Table (IYPT) will bring chemistry into the future as The Olympic & Paralympic Games in Tokyo in 2020.

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