40-Godišnjica institucije Cambridge Crystallographic Data Centre posvećene pohranjivanju podataka o molekularnim i kristalnim strukturama -

The article is dedicated to 40th anniversary of The Cambridge Crystallographic Data Centre (CCDC), the world-known centre (http://www.ccdc.cam.ac.uk) responsible for deposition and control of crystallographic data, including atomic coordinates that define the three-dimensional structures of organic molecules and metal complexes containing organic ligands. Cambride Structural Database (CSD), one among the first established electronic databases, nowadays is the most significant crystallographic database in the world. CSD has about 400,000 deposited structures. The use of the extensive database, which is growing rapidly, needs support of efficient and sophisticated software for searching, analysing and visualising structural data. The seminal role of CSD in the research related to crystallography, chemistry, material sciences, solid state physics and chemistry, life sciences, pharmacology, and in particular in drug design, has been documented in more than 1300 scientific papers. The important issues of CCDC are the accuracy of deposited data and development of software that enables a wide variety of applications. Such demanding project requires higly competent team of experts; thus the article brings into focus the scientific approach of the team based on the long tradition in crystallography, modelling and informatics. The article is not dedicated to 40th anniversary of the centre only, but it also reveals how Cambridge Structural Database can be used in the research and teaching. The use of electronic media and computer graphics makes data mining" very efficient and useful but also esthetically appealing due to the molecular architecture. At the Rudjer Bošković Institute, Zagreb, Croatia there is The National Affiliated Centre of Cambridge Crystallographic Data Centre responsible for communication and dissemination of CSD in Croatia, Slovenia and Macedonia. The use of CSD is illustrated by two examples performed and published by the presenting authors: a) the analysis of the less-common hydrogen bonds with the ester oxygen atom as a proton acceptor, and b) topological analysis of tubular assemblies of macrocyclic polythianes extensively described in the references 24 and 28

Preparation and Characterization of Some Sodium-, Rubidium-, Cesium- and Ammonium-Oxodiperoxooxalato-Molybdates (VI) and Tungstates (VI)

Potassium derivatives of oxodiperoxooxalato- molybdates and tungstates: were prepared before1>2 studied by infrared Raman3 and X-ray methods4•5 .The crystal structure of corresponding molybdate with literature survey was published recently4

Spontaneous Precipitation in the System Uranyl(2+ )nitrate Potassium Hydroxide - Phosphoric Acid - Water

The precipitation system U02(NOs)2-KOH-H3P04-H20 (at 298 K) aged for 1 day and for 30 days is examined ([U02(NOs)2] = = 1 · 10-a mol dm-3, [KOH] varied from 1 · 10-6 to 6 · 10-1 mol dm-3, [H3P04] from 2 · 10-4 to 6 · 10-1 mol dm-3 and 1.5 <pH< 11.5). The precipitation and phase boundaries are determined. The solid phases U02HP04 · 4 H20(s) and (U02)s(P04)2 · 8 H20 are stable at [KOH] < 1 · 10-3 mol dm-3, 1.5 <pH < 4.0. Uranates precipitate at pH > 9.5. The stability region of KU02P04 · 3 H20(s) is found at high concentrations of KOH and H3P04. X-ray diffraction pattern of this compound is given. According to the precipitation boundary after 30 days (equilibrium conditions) the solubility product of KU02P04 · 3 H20 is determined: log ([K+] · · [U022+] [P043-]) = -- 26.28 (at I =0 mol dm-3)

Identification and Characterization of Alkaline Uranyl(2 +) Phosphates

The spontaneous precipitation in the systems U02(N03)2- -MOH-HaP04--H20 and U02(N03)2-MNOa-H3P04- H20 (M = = Li, Na, K, Rb, Cs) is examined. The formation of alkaline- uranyl(2+) phosphates polyhydrates is detected: M[U02P04] · · n H20 (n = 4 for M = Li, n = 3 for M = Na, K, Rb and n = 2.5 for M =Cs). The X-ray powder patterns of these compounds are determined and compared with that of H30[U02P04] · 3 H20. A close structural relation within this series is observed. The size of the alkaline ionic species in the particular compound affects the content of crystalline water in the unit cell

Opažanja vaspitača i roditelja o ulozi dece posmatrača u vršnjačkom nasilju

Introduction. Peer violence impacts the development of children who are victims of violence, but children who witness violence are also prone to experience consequences pertaining to their socio-emotional development. The state should provide dedicated support to intervention programmes in preschool institutions aimed at preventing and suppressing peer violence, which would focus on children who are witnesses, i.e., observers of violence. Objectives. This research was aimed at analysing the perceptions of preschool teachers and parents about the role of children observers in peer violence. Methods. The sample consisted of preschool teachers employed in preschool institutions in several cities in Serbia (n = 104) and parents whose children attended preschools (n = 84). For the purposes of the research, an adapted Likert-type scale was used, which assessed the role of children “observers” of peer violence and the possibilities of developing support programmes for children exposed to violence. The instrument was developed based on a pilot study on the role of children observers in bullying. Results. Research results showed that the perceptions of parents pertaining to the role of children observers in peer violence were statistically significantly different in relation to the opinions of preschool teachers. Parents believed that children who were observers of peer violence were not sufficiently involved in intervention programmes for the prevention and suppression of peer violence in preschool institutions. Conclusion. These findings have significant practical implications for the planning of initiatives in preschool institutions aimed at fostering a supportive environment in which children who witness peer violence would play a prominent role.Uvod: Vršnjačko nasilje ostavlja najviše posledica na razvoj deteta koje je žrtva nasilništva, ali isto tako i deca posmatrači mogu imati posledice u oblasti socioemocionalnog razvoja. Interventnim programima u predškolskoj ustanovi koji imaju za cilj prevenciju i suzbijanje vršnjačkog nasilja, a u čijem su fokusu posmatrači, država treba da pruži snažnu podršku. Cilj: Istraživanje je imalo za cilj da se analiziraju opažanja vaspitača i roditelja oulozi dece posmatrača u vršnjačkom nasilju. Metode: Uzorak su činili vaspitači zaposleni u predškolskim ustanovama (n = 104) i roditelji čija deca pohađaju vrtiće (n = 84) u više gradova u Srbiji. Za potrebe istraživanja korišćena je prilagođena skala Likertovog tipa kojom se procenjuje uloga dece „posmatrača” u bulingu i mogućnosti razvijanja programa podrške vršnjacima koji su izloženi nasilništvu. Instrument je razvijen na osnovu pilot-istraživanja o ulozi dece posmatrača u bulingu. Rezultati: Rezultati istraživanja pokazali su da se opažanja roditelja u vezi sa ulogom dece u vršnjačkom nasilju statistički značajno razlikuju u odnosu na percepcije vaspitača. Roditelji smatraju da deca posmatrači vršnjačkog nasilja nisu dovoljno uključeni u interventne programe prevencije i suzbijanja vršnjačkog nasilja u predškolskim ustanovama. Zaključak: Ovi rezultati imaju značajne praktične implikacije, jer ukazuju kako da predškolske ustanove pokrenu programe koji su usmereni na stvaranje pozitivne klime u grupi u kojoj bi deca posmatrači vršnjačkog nasilja bili značajan faktor

Molecular Mechanics and SCF MO Conformational Analysis of Indol-3-ylacetic Acid Phytohormone (Auxin)

Conformational analysis of indol-3-ylacetic acid (IAA)-plant growth hormone has been performed using molecular mechanics and the ab initio SCF MO theory. The equilibrium geometry of IAA has been determined. Relative energies of alternative conformations, their charge distribution, dipole moment and energy barriers between them have been calculated. The position of the carboxyl group relative to the indole ring depends on two torsion angles, Tl(C2-C3-C8-C9) and T2(C3-C8-C9=02). Rotational barriers for these two angles were explored and it emerged that both rotations (about the C3-C8and C8-C9 bonds) can be accomplished in a reasonable time period at room temperature (the barrier height is about 4.6-10.9 (TI) and 1.7-3.8 (T2) kJ/mol respectively, according to ab initio calculations. Ab initio (GAMESS)and molecular mechanics (DISCOVER (CVFF and cff91), SYBYL(TRIPOS) and MM2(87), calculations revealed qualitatively the same shape of potential energy surface (E =f(Tl, T2)). However, energy differences between various conformations depend on the basis set (ab initio calculations) and force field (molecular mechanics) used

Preparation and Structure of Disodium Thorium Bisphosphate, Na2Th(P04 )2

Na2Th(P04 ) 2 was investigated as a part of our study in the structure chemistry of alkali thorium and zirnonium orthophosphates

Chirality - The forthcoming 160th Anniversary of Pasteur\u27s Discovery

Prikaz o kiralnosti posvećen je 100. godišnjici rođenja Nobelovca Vladimira Preloga i predstojećoj 160. godišnjici Pasteurovog otkrića kiralnosti soli vinske kiseline. Pojavu kiralnosti u prirodi prepoznali su umjetnici i graditelji koristeći je u svojim djelima što je ilustrirano primjerima u uvodu. Napretkom znanosti kroz povijest do danas šire se spoznaje o kiralnosti i gotovo je nemoguće obuhvatiti sve njezine aspekte i primjene. Opisana su ključna povijesna otkrića vezana uz pojavu zakretanja ravnine polariziranog svjetla kao posljedicu kiralnosti te otkrića Pasteura i lorda Kelvina. Kiralnost se susreće u fizici elementarnih čestica kao i u svim područjima kemije: analitičkoj i organskoj kemiji, kemiji prirodnih spojeva, medicinskoj i farmaceutskoj kemiji, biokemiji i biotehnologiji, kao i molekularnoj biologiji. Kratko je opisano širenje spoznaja o kiralnosti i fizikalne osnove molekularne kiralnosti. Sustavno su definirane: geometrijska, topološka i konformacijska kiralnost. Povezanost simetrije i kiralnosti dolazi do izražaja i u kristalografiji. Kako je rendgenska strukturna analiza metoda kojom se jednoznačno određuje molekularna arhitektura, neosporno je da se pri tome utvrđuje i apsolutna konfiguracija molekula Bijvoetovim pristupom. Sažeto su opisane dvije metode za određivanje apsolutne konfiguracije: metoda rendgenske difrakcije i kružnog dikroizma. U skladu s obilježavanjem značajnog jubileja, prikaz je orijentiran na ulogu kiralnosti u (stereo)kemiji. To je u skladu s E. L. Elielovim pristupom koji stereokemiju smatra načinom gledanja na kemiju, a ne granom kemije. Taj pristup omogućava sagledavanje različitih aspekata kiralnosti i usuglašavanje postojećih nepotpunih definicija o kiralnosti molekula, što zacijelo otvara nove primjene. Budućnost nam nudi da više saznamo o kiralnosti u službi komunikacije molekula koje upravljaju našim životnim procesima. U tijeku su eksperimenti priprave raznorodnih dinamičkih kiralnih supramolekula iz akiralnih molekula i predstoji istražiti kako se to korisno može upotrijebiti. Istraživanje izotopne kiralnosti kvantno-kemijskim metodama omogućit će razumijevanje odstupanja od zakona pariteta i rasvijetliti fizikalne osnovice molekularne kiralnosti.The presented review on chirality is dedicated to the centennial birth anniversary of Nobel laureate Vladimir Prelog and 160 years of Pasteur\u27s discovery of chirality on tartrates. Chirality has been recognized in nature by artists and architects, who have used it for decorations and basic constructions, as shown in the Introduction. The progress of science through history has enabled the gathering of knowledge on chirality and its many ways of application. The key historical discoveries about the rotation of polarized light as a consequence of molecular chirality and findings of Pasteur and Lord Kelvin are described. Chirality can be found in physics of elementary particles and in many fields of chemistry: analytical and organic chemistry, chemistry of natural compounds, medicinal and pharmaceutical chemistry, biochemistry and biotechnology, and molecular biology. The development of knowledge about chirality and its physical background are briefly described. Definitions for geometrical, topological, and conformational chirality are given accompanied by numerous examples of molecules exhibiting such features. The relations between symmetry and chirality in crystallography are exposed. X-ray crystallography is a method of choice for unambiguous determination of molecular architecture, including the absolute configuration of the molecule using Bijvoet\u27s approach. Two methods of determination of absolute configuration by X-ray diffraction and circular dichroism are briefly discussed. To mark two significant jubilees, the essay is dedicated to the role of chirality in stereochemistry. Stereochemistry is not a branch of chemistry but rather a view at chemistry, as considered by E. L. Eliel; this approach is respected in the essay presented. This very approach leads to various aspects of chirality and brings to the consistency of many definitions. The future will bring us knowledge on the role of chirality in communications among molecules, which guide our life processes. The synthesis of various dynamically chiral supramolecules from achiral molecules and preparations of conjugated homochiral polymers will offer new types of biosensors, artificial enzymes and some sophisticated materials. The research of isotopic chirality by quantum-chemical methods reveals some parity-violating effects and shed more light on the physical bases of molecular chirality

The 100th Anniversary of X-Ray Crystallography

The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. W. L. Bragg Stogodišnjica rendgenske kristalografije veže se uz prvi pokus difrakcije rendgenskih zraka koji su s kristalom modre galice izveli njemački fizičari W. Friedrich i P. Knipping prema ideji i teorijskom predviđanju M. von Lauea 1912. Matematička formulacija pojave, kao i temeljne postavke znanosti o građi kristala - kristalografije, u to vrijeme vezane uz mineralogiju, pogodovale su razvitku metode za određivanje geometrijske strukture tvari na atomnoj razini. Već su 1913. otac i sin Bragg započeli stvarati temelje za primjenu rendgenske difrakcije u određivanju kristalnih struktura jednostavnih molekula. Povijesni primjeri određivanja struktura od kuhinjske soli do složenih, za život bitnih, (makro)molekula, kao globularnih proteina hemoglobina i mioglobina, DNA, vitamina B12, te novog otkrića ribozima, ilustriraju razvojni put rendgenske strukturne analize. Otkriće trodimenzijskih struktura tih molekula metodom rendgenske difrakcije pokrenulo je nove znanstvene discipline poput molekularne biofizike, molekularne genetike, strukturne molekularne biologije, bioanorganske kao i organometalne kemije i niza drugih disciplina. Otkriće i razvoj rendgenske kristalografije revolucioniralo je naše spoznaje u svim područjima prirodnih znanosti: fizici, kemiji, biologiji, geološkim znanostima i znanosti o materijalima. Znanstvena javnost prepoznala je ta temeljna znanstvena postignuća (uključujući i otkriće X-zraka) dodijelivši Nobelove nagrade tridesetdevetorici znanstvenika i dvjema znanstvenicama. Eksplozivan razvoj znanosti i tehnologije tijekom 20. i 21. stoljeća temelji se na spoznajama o detaljnoj trodimenzijskoj građi molekula i njome predviđenih i objašnjenih fizičkih, kemijskih, bioloških i farmakoloških svojstava molekula. Jedan od svježih primjera, koji je bilo teško predvidjeti, uspješna je i nedovršena priča o grafenima, koja puni naslovnice vodećih znanstvenih časopisa kao što su Science, Nature, Nature Materials, Nature Nanotechnology, Nature Chemistry i Nature Physics. Suvremena kristalografska istraživanja pokrivaju široko područje znanosti i veoma su inovativna, te nije uputno predviđati u kojim će se smjerovima nastaviti razvijati.The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them. W. L. Bragg The 100th anniversary of X-ray crystallography dates back to the first X-ray diffraction experiment on a crystal of copper sulphate pentahydrate. Max von Laue designed the theoretical background of the experiment, which was performed by German physicists W. Friedrich and P. Knipping in 1912. At that time, the mathematical formulation of the phenomenon and the fundamental concepts of crystallography were subjects of mineralogy. Altogether, they facilitated the development of methods for determination of the structure of matter at the atomic level. In 1913, father and son Bragg started to develop X-ray structure analysis for determination of crystal structures of simple molecules. Historic examples of structure determination starting from rock salt to complex, biologically important (macro)molecules, such as globular proteins haemoglobin and myoglobin, DNA, vitamin B12 and the recent discovery of ribozyme, illustrate the development of X-ray structural analysis. The determination of 3D structures of these molecules by X-ray diffraction had opened new areas of scientific research, such as molecular biophysics, molecular genetics, structural molecular biology, bioinorganic chemistry, organometallic chemistry, and many others. The discovery and development of X-ray crystallography revolutionised our understanding of natural sciences – physics, chemistry, biology, and also science of materials. The scientific community recognised these fundamental achievements (including the discovery of X-rays) by awarding twenty-eight Nobel prizes to thirty-nine men and two women. The explosive growth of science and technology in the 20th and 21st centuries had been founded on the detailed knowledge of the three-dimensional structure of molecules, which was the basis for explaining and predicting the physical, chemical, biological and pharmacological properties of molecules. A most recent and striking example is the still unfinished story of graphenes, occupying the front pages of leading scientific journals, such as Science, Nature, Nature Materials, Nature Nanotechnology, Nature Chemistry and Nature Physics. Contemporary crystallographic research covers numerous scientific domains, and it is a very innovative area of science. Who would dare to be a prophet and foresee future findings? </div