Conducting olefin metathesis reactions in air : breaking the paradigm

The authors gratefully acknowledge the Royal Society (University Research Fellowship to CSJC) and the EC (CP-FP 211468-2 EUMET) for funding.The first study of low catalyst loading olefin metathesis reactions in air is reported. TON values of up to 7000 were obtained using non-degassed solvents with commercially available pre-catalysts Caz-1, Hov-II and Ind-II. The simple experimental conditions allow olefin metathesis reactions to be carried out on the benchtop using technical grade solvents in air.PostprintPeer reviewe

A straightforward metal-free synthesis of 2-substituted thiazolines in air

The authors are grateful to the Royal Society (University Research Fellowship to CSJC) for financial support.A base-catalysed procedure for the synthesis of 2-substituted thiazolines from nitriles and cysteamine hydrochloride under solvent-free conditions is presented. This straightforward approach allows high conversion for a broad range of nitriles and an easy isolation of the desired products.PostprintPeer reviewe

Nonlinear Analysis of Reinforced Concrete Beams using FEM with Smeared Crack Approach, Mohr’s Failure Criteria, and The Tomaszewicz Model

Cracking has a predominant effect on the failure mode of reinforced concrete beams. Their presence results a nonlinear stiffness behavior. Previous research work explained the concrete cracking process due to the exceeding of the major tensile principal stress to the concrete tensile strength only. The effect of the minor principal stress is neglected. This incorrectness results a less precise prediction of crack propagation and beam failure. Hence, an advanced analysis predicting the occurrence of cracks and taking into account the presence of biaxial principal stresses, is developed. The nonlinear finite element analysis is used to calculate stress and strain. To model steel reinforcement and the concrete cracking, the smeared element and smeared crack approach are chosen. The material behavior is consider nonlinear, while the bond slip effect and dowel action is neglected. The existence of cracks as a result of the combination of normal and shear stress is predicted based on the Mohr’s failure criteria. The uniaxial concrete stiffness-modulus, not constant under incremental loading, is generated by the Tomaszewicz model. The load–displacement curves of analyzed beams are validated with identical laboratory tested specimens

Aerobic synthesis of N-sulfonylamidines mediated by N-heterocyclic carbene copper(I) catalysts

The authors gratefully acknowledge the EPSRC National Mass Spectroscopy Facilities for the HMRS analysis at the University of Swansea.A new catalytic strategy for the one-pot synthesis of N-sulfonylamidines is described. The cationic copper(I) complexes were found to be highly active and efficient under mild conditions in air and in the absence of solvent. A copper acetylide is proposed as key intermediate in this transformation.Publisher PDFPeer reviewe

Synthetic Access to Ring-Expanded N-Heterocyclic Carbene (RE-NHC) Copper Complexes and their Performance in Click Chemistry

The facile syntheses of ring-expanded N-heterocyclic carbene (RE-NHC) copper(I) halide complexes are reported. The method makes use of a weak inorganic base in a green solvent. The reaction times can be greatly reduced by use of this weak-base route under microwave irradiation. The easy access to these complexes permits an evaluation of the catalytic activity and reaction profiling of [Cu(RE-NHC)X] complexes in the Huisgen 1,3-cycloaddition reaction

Selective NaOH-catalysed hydration of aromatic nitriles to amides

The authors gratefully acknowledge the Royal Society (University Research Fellowship to CSJC)The selective synthesis of aromatic and heteroaromatic amides through base-catalysed hydration of nitriles was achieved using inexpensive and commercially available NaOH as the only catalyst. A wide range of nitriles was selectively converted to their corresponding amides. Kinetic studies show that the double hydration of nitriles towards undesirable carboxylic acids is negligible under our reaction conditions.PostprintPeer reviewe

ANALIZA SUSTAVA ZA UNUTARNJE LOCIRANJE

Recently, due to advances in the development of various technologies which can be used for locating, it is possible to develop systems which include software solutions for the user locationing and guidance in the interior, closed or covered areas where the existing location technologies and systems for locating and guidance applicable at open, outdoor areas cannot be used. This paper analyses the available hardware, software and network technologies which can be used for creating a positioning system for interior, closed or covered area. The paper analyses technologies which can be used in such distributed systems for the implementation of functionalities that are needed or required in the Indoor Positioning System (IPS). The paper describes the concept of the IPS system. It presents the IPS systems available on the market. It shows the technologies that can be used to implement the IPS system and the analyses of categories which affect the IPS system implementation. The paper demonstrates that none of the technologies analysed meet all of the observed categories while the BLE technology achieves the most favourable results in individual categories.Zbog napretka u razvoju raznih tehnologija koje se mogu koristiti za lociranje, u posljednje vrijeme razvijaju se sustavi koji uključuju programska rješenja za lociranje i navođenje korisnika u unutarnjem, zatvorenom ili natkrivenom prostoru, gdje se postojeće tehnologije za lociranje i sustavi za lociranje i navođenje koje se primjenjuju kod otvorenih, vanjskih prostora, ne mogu koristiti. U radu se analiziraju dostupne hardverske, softverske i mrežne tehnologije kojima je moguće izraditi sustav za unutarnje lociranje, odnosno tehnologije kojima takav distribuirani sustav po svom karakteru i implementiranim funkcijama postaje sustav za lociranje u zatvorenom prostoru (IPS, engl. Indoor Positioning System). Opisan je koncept IPS sustava. Prikazani su gotovi IPS sustavi dostupni na tržištu. Pokazane su tehnologije koje se mogu koristiti za implementaciju IPS-a i izrađena analiza kategorija koje utječu na implementaciju IPS-a. Pokazano je da niti jedna tehnologija ne zadovoljava sve promatrane kategorije, no BLE tehnologija omogućuje ostvarenje najpovoljnijih rezultata po pojedinim kategorijama

[Pd(NHC)(μ-Cl)Cl]2 : versatile and highly reactive complexes for cross-coupling reactions that avoid formation of inactive Pd(I) off-cycle products

Authors thank Rutgers University (M.S.), the NSF (CAREER CHE-1650766, M.S.), and the NIH (1R35GM133326, M.S.) for financial support. The Bruker 500 MHz spectrometer used in this study was supported by the NSF-MRI grant (CHE-1229030). For work conducted in Belgium, S.P.N. and C.S.J.C. wish to thank the UGent BOF (starter and senior research grants). Umicore AG is thanked for gifts of materials. A.P. is a Serra Húnter Fellow and ICREA Academia Prize 2019 holder. A.P. thanks the Spanish MICINN for project PGC2018-097722-B-I00.The development of more reactive, general, easily accessible, and readily available Pd(II)–NHC precatalysts remains a key challenge in homogeneous catalysis. In this study, we establish air-stable NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, as the most reactive Pd(II)–NHC catalysts developed to date. Most crucially, compared with [Pd(NHC)(allyl)Cl] complexes, replacement of the allyl throw-away ligand with chloride allows for a more facile activation step, while effectively preventing the formation of off-cycle [Pd2(μ-allyl)(μ-Cl)(NHC)2] products. The utility is demonstrated via broad compatibility with amide cross-coupling, Suzuki cross-coupling, and the direct, late-stage functionalization of pharmaceuticals. Computational studies provide key insight into the NHC–Pd(II) chloro-dimer activation pathway. A facile synthesis of NHC–Pd(II) chloro-dimers in one-pot from NHC salts is reported. Considering the tremendous utility of Pd-catalyzed cross-coupling reactions and the overwhelming success of [Pd(NHC)(allyl)Cl] precatalysts, we believe that NHC–Pd(II) chloro-dimers, [Pd(NHC)(μ-Cl)Cl]2, should be considered as go-to precatalysts of choice in cross-coupling processes.Publisher PDFPeer reviewe

A mechanistically and operationally simple route to metal-N-heterocyclic carbene (NHC) Complexes

We gratefully acknowledge VLAIO (SBO project CO2PERATE), King Saud University (Distinguished Scientist Fellowship Program) and King Abdullah University of Science and Technology for support. The Special Research Fund (BOF) of Ghent University is also acknowledged (Doctoral Scholarship to N.V.T.). COST action (CA15106-CHAOS) is thanked for mobility support to N.V.T. Umicore AG is acknowledged for generous gifts of materials.We have been puzzled by the involvement of weak organic and inorganic bases in the synthesis of metal‐N‐heterocyclic carbene (NHC) complexes. Such bases are insufficiently strong to permit the presumed required deprotonation of the azolium salt (the carbene precursor) prior to metal binding. Experimental and computational studies provide support for a base‐assisted concerted process that does not require free NHC formation. The synthetic protocol was found applicable to a number of Transition Metal‐ and Main Group‐centered NHC compounds and could become the synthetic route of choice to form M‐NHC bonds.PostprintPeer reviewe

CONTRIBUTION TO THE REVALUATION OF IVAN MEŠTROVIĆ ARCHITECTURAL LEGACY IN LIGHT OF MUSEOLOGICAL AND INHERITANCE CONSIDERATION

Arhitektonski opus Ivana Meštrovića u kontekstu vremena i prilika u kojima je umjetnik stvarao zasigurno je izniman doprinos hrvatskom graditeljstvu prve polovice 20. st. Njegova valorizacija višestruko je važna, osobito s muzeološkoga, stilskoga i programatskoga gledišta. U slojevitom eklekticizmu svih Meštrovićevih ostvarenih i neostvarenih arhitektonskih te urbanističkih projekata stilska raščlamba i diferencijacija svakoga pojedinog objekta i nacrta postavlja se kao nužna polazišna točka koju naknadno slijedi povijesnoumjetničko vrednovanje i muzeološke preferencije. Neosporno višejezičan vokabular Meštrovićevih arhitektonskih zamisli za sve je vrijeme njegova stvaralaštva pod kontinuiranim utjecajem različitih arhitektonskih rječnika u širokome vremenskom rasponu od starovjekovnih civilizacija do modernih tekovina. U umjetnikovu opusu mogu se posve jasno iščitati prostorne, tlocrtne, dispozicijske i pejzažne zadanosti klasičnoga arhitektonskog promišljanjaThe article analyzes the problem of the architectural legacy of Ivan Meštrović with the intention of seeing the importance of this under-examined area of his work. An analytical examination, scientific analysis and subsequent popularization of the architectural oeuvre of Ivan Meštrović and, in general, its contribution to the national and European architecture of the first half of the 20th century is important for a better scientific and museological evaluation of the architectural heritage. The architecture of Ivan Meštrović tends to be undervalued in comparison with his sculptural production. The research into and the systematic treatment and protection of the architectural monuments of this great artist can provide us with an insight into a new world of space, volume and shapes, and of design, conceptual and construction solutions. In the sea of dissimilarity, the models and various stylistic narrations reveal to us Meštrović the architect. The paper is structured in such a way that the first part refers to the artist’s education and the acquisition of basic architectural knowledge during his study in Vienna, helping him to form an architectural style of his own through the prism of the influences of various cultures and civilisations. In the second part the focus is directed at separate analysis and interpretation of designed and constructed buildings, as well as those whose ideas were not realized. Monuments are categorized into four groups according to theme and use: memorial buildings, religious buildings, creative and living spaces, public buildings. An analysis of Meštrović’s architecture reveals a pluralism of styles, within which several dominant sources stand out. Primarily these are classicism, then the medieval religious architecture of Dalmatia, Egyptian monumentalism and the influences of his many collaborators