Synthesis and evaluation of chiral stationary phases containing N-(1-arilpropil)-3, 5-dinitrobenzamide selector

Pripravljena je serija od devet novih kiralnih nepokretnih faza (KNF) četkolikog tipa koje karakterizira maksimalno smanjen broj akiralnih mjesta interakcije. Sintetizirane KNF se razlikuju u aromatskoj skupini vezanoj neposredno na kiralni centar. Kiralni selektor, N-(1-arilpropil)-3, 5-dinitrobenzamidna jedinica, ima sva svojstva dobrog selektora – rigidan je, te sadrži snažnu π-akceptorsku (3, 5-dinitrobenzoilnu) i snažnu π-donorsku aromatsku skupinu. Ključni međuprodukti u sintezi su enantiomerno čisti alil-aril-amini koji su priređeni enzimskom rezolucijom. Racemični amini su dobiveni Overmanovom pregradnjom iz acikličkih imidata. Alkoholi, koji su polazni spojevi za odgovarajuće imidate, su priređeni iz dostupnih aldehida Knoevenagelovom reakcijom i redukcijom nastalog estera. Sintetizirani enantiomerno čisti selektori se vežu na silikagel na način koji ne uvodi dodatne polarne skupine u strukturu KNF. Pripremljene KNF su testirane na trideset različitih racemičnih spojeva. Dobiveni rezultati su uspoređeni te su dobiveni podaci o utjecaju aromatske skupine na enantioseparaciju analita. Kromatografska evaluacija je pokazala da nove KNF odjeljuju enantiomere širokog spektra spojeva, a najkvalitetnije rezultate su pokazale one koje sadrže selektor s naftilnim supstituentom.A set of nine new brush-type chiral stationary phases (CSPs) which possess fewer achiral adsorption sites was synthesized. Prepared CSPs differ in aromatic units directly linked to the chiral center. Chiral selector, the N-(1-arylpropyl)-3,5-dinitrobenzamide unit, has all the properties of a good selector – it is rigid and contains a strong π-accepting 3,5-dinitrobenzoyl and a strong π-donating aromatic group. The key intermediates in the synthesis are enantiomericaly pure allyl aryl amines prepared by enzymatic resolution. Racemic amines were obtained by Overman rearrangement of acyclic imidates. Imidates were prepared from the corresponding alcohols which were synthesized from available aldehydes in a Knoevenagel reaction followed by ester reduction. The method for binding the chiral selector to silica gel was selected in such a manner that additional polar groups were not introduced. Thirty various racemic analytes were used to evaluate the prepared CSPs. The results were compared and the influence of the aromatic unit on enantioseparation of the analytes was demonstrated. Chromatographic evaluation showed that the new CSPs separate enantiomers of a wide range of compounds and the best results demonstrate CSPs that contain a selector with the naphthyl substituent

Synthesis and Mesomorphic Properties of Novel Bent-shaped Naphthyl Diketones

The synthesis and liquid-crystalline properties are reported for novel naphthyl-based diketones incorporating variant terminal chains and lateral fluoro- substitution. Newly prepared materials exhibit a broad temperature range of the nematic phase. The study demonstrates how subtle structural modifications can be exploited to alter the efficiency of molecular packing and consequently the thermal behaviour. This work is licensed under a Creative Commons Attribution 4.0 International License

Resorcinol-, catechol- and saligenin-based bronchodilating beta2-agonists as inhibitors of human cholinesterase activity

We investigated the influence of bronchodilating 2-agonists on the activity of human acetylcholinesterase (AChE) and usual, atypical and fluoride-resistant butyrylcholinesterase (BChE). We determined the inhibition potency of racemate and enantiomers of fenoterol as a resorcinol derivative, isoetharine and epinephrine as catechol derivatives, and salbutamol and salmeterol as saligenin derivatives. All of the tested compounds reversibly inhibited cholinesterases with Ki constants ranging from 9.8 µM to 6.4 mM, and had the highest inhibition potency toward usual BChE, but generally none of the cholinesterases displayed any stereoselectivity. Kinetic and docking results revealed that the inhibition potency of the studied compounds could be related to the size of the hydroxyaminoethyl chain on the benzene ring. The additional - interaction of salmeterol’s benzene ring and Trp286 and hydrogen bond with His447 probably enhanced inhibition by salmeterol which was singled out as the most potent inhibitor of all the cholinesterases

Photothermal Reactions of Nitrosobenzene and Halonitrosobenzenes in Solid-state

Photothermal reactions of nitrosobenzene, m-chloronitrosobenzene, and p-chloronitrosobenzene were studied in solid-state by IR spectroscopy at low temperatures and by X-ray powder diffraction. It was found for the first time that photothermal cycle (photolytic dissociation followed by thermal dimerization) could successively be performed also with Z-configured nitrosobenzene. Halonitrosobenzenes with E-configuration afforded different photo behavior depending on the position of halogen atom on the benzene ring: while m-halonitrosobenzenes do not dissociate under UV irradiation, p-chloronitrosobenzene, as well as previously studied p-bromonitrosobenzene photolyses very efficiently with recovering of the original crystal phase. Kinetics of thermal dimerization was measured in solid-state, and it was found that the reaction phase transformation occur as a two-dimensional growth through the crystal

Multivalent Noncovalent Interfacing and Cross-Linking of Supramolecular Tubes

Natural supramolecular filaments have the ability to cross-link with each other and to interface with the cellular membrane via biomolecular noncovalent interactions. This behavior allows them to form complex networks within as well as outside the cell, i.e., the cytoskeleton and the extracellular matrix, respectively. The potential of artificial supramolecular polymers to interact through specific noncovalent interactions has so far only seen limited exploration due to the dynamic nature of supramolecular interactions. Here, a system of synthetic supramolecular tubes that cross-link forming supramolecular networks, and at the same time bind to biomimetic surfaces by the aid of noncovalent streptavidin–biotin linkages, is demonstrated. The architecture of the networks can be engineered by controlling the density of the biotin moiety at the exterior of the tubes as well as by the concentration of the streptavidin. The presented strategy provides a pathway for designing adjustable artificial supramolecular superstructures, which can potentially yield more complex biomimetic adaptive materials

Induced smectic phase in binary mixture of twist-bend nematogens

The investigation of liquid crystal (LC) mixtures is of great interest in tailoring material properties for specific applications. The recent discovery of the twist-bend nematic phase (NTB) has sparked great interest in the scientific community, not only from a fundamental viewpoint, but also due to its potential for innovative applications. Here we report on the unexpected phase behaviour of a binary mixture of twist-bend nematogens. A binary phase diagram for mixtures of imino- linked cyanobiphenyl (CBI) dimer and imino- linked benzoyloxy-benzylidene (BB) dimer shows two distinct domains. While mixtures containing less than 35 mol % of BB possess a wide temperature range twist-bend nematic phase, the mixtures containing 55–80 mol % of BB exhibit a smectic phase despite that both pure compounds display a Iso–N–NTB–Cr phase sequence. The phase diagram shows that the addition of BB of up to 30 mol % significantly extends the temperature range of the NTB phase, maintaining the temperature range of the nematic phase. The periodicity, obtained by atomic force microscopy (AFM) imaging, is in the range of 6– 7 nm. The induction of the smectic phase in the mixtures containing 55–80 mol % of BB was confirmed using polarising optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction. The origin of the intercalated smectic phase was unravelled by combined spectroscopic and computational methods and can be traced to conformational disorder of the terminal chains. These results show the importance of understanding the phase behaviour of binary mixtures, not only in targeting a wide temperature range but also in controlling the self-organizing processes

Technical inspection of machines for crop protection

Ulaskom Republike Hrvatske u Europsku uniju, usklađuje se zakonodavstvo sa europskom direktivom 2009/128/EC, prema kojoj svi strojevi za zaštitu bilja moraju imati valjani tehnički pregled. Konačni nacrt zakona stupio je na snagu 24. siječnja 2014. godine (NN 14/14), prema kojem se tehnički pregled za sve strojeve u eksploataciji mora obaviti do 26. studenog 2016. godine. Trenutno u RH tehnički pregled obavilo je otprilike 16.000 strojeva koji su upisani u FIS bazu podataka. Glavnina strojeva sa valjanom naljepnicom o tehničkom pregledu je iz panonskog dijela države, a pretpostavka je da pregled mora obaviti još cca. 15 000 strojeva. Ministarstvo poljoprivrede sa Odjelom za održivu uporabu pesticida je nadležno za provedbu navedenog zakona, a tehnički pregled obavlja 11 mobilnih ispitnih stanica. Uspostavljen je sustav edukacije inspektora za tehnički pregled strojeva koji se obavlja prema normi EN 13790. Valjanost tehničkog pregleda izdaje se na rok od 3 godine, dok se novim strojevima (kupljeni nakon 01.01.2013. godine) izdaje naljepnica sa rokom od 5 godina, bez tehničkog pregleda, samo sa upisom u FIS bazu.By joining the Republic of Croatia with the European Union, legislation is aligned with the European Directive 2009/128/EC, according to which all plant protection machines must have a valid technical inspection. The final law draft entered into force on January 24, 2014 (NN 14/14), whereby a technical inspection of all machines in exploitation must be completed by November 26, 2016. Currently in the Republic of Croatia a technical inspection was carried out approx. 16 000 machines entered in the FIS database. Most of the machines with a valid label on the technical inspection are from the Pannonian part of the state, and the assumption is that the inspection must be accomplished by approx. 15 000 machines. The Ministry of Agriculture with the Department for Sustainable Use of Pesticides is competent for the implementation of this law, and a technical inspection is carried out by 11 mobile test stations. An inspectors’ education system has been established and the technical inspection is carried out according to EN 13790 standard. The validity of the technical inspection is issued for a period of 3 years, while the new machines (purchased after 01.01.2013.), received a 5-year valid sticker without a technical inspection, only with the entry into the FIS database