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Dear colleagues, we are extremely honoured to present to you the Proceedings of the international conference 19th Ružička Days, which was successfully held on September 21–23, 2022, in Vukovar, Croatia, in the hometown town of our famous Croatian scientist and first Nobel laureate, professor Leopold (Lavoslav) Ružička. The main goals of the Conference were to promote excellence, originality and innovation of interdisciplinary scientific research as well as the practical application of the obtained results through collaboration with industry, emphasizing thus the recognizable slogan of the Ružička Days conference: "Today Science – Tomorrow Industry". In addition, the Conference gave the opportunity for meetings, exchanging the ideas, opinions, experiences and cooperation among participants from different working surroundings. It is also important to point out that since 2008, within the international conference Ružička Days, Meeting of Young Chemists has also been held, where high school students, with the help of their mentors, present papers in the field of chemistry, with the aim to direct students and young people to the technical and natural sciences, especially chemistry. In its seventh issue (2011, 2013, 2015, 2017, 2019, 2021) the Proceedings publishes scientific and professional full papers of high quality in the following sections: Chemical analysis and synthesis (10), Chemical and biochemical engineering (3), Food technology and biotechnology (4), Chemistry in agriculture and forestry (1), Environmental protection (9) and 8th Meeting of Young Chemists (3). Full-length papers were subjected to an international review procedure done by eminent experts from the corresponding fields, to whom we express our gratitude, but they were not subjected to linguistic proofreading. On behalf of the Scientific and Organizing Committee of the 19th Ružička Days we cordially thank all the authors, reviewers, participants, lecturers, organizers, especially the international organizers EuCheMS and EHEDG, auspices and sponsors, and all the others who, in any way, supported the Conference and contributed to the preparation of the Proceedings, especially to our highly skilled and committed associates, who have put a lot of effort in the preparation of these Proceedings. At the very end, special thanks to our young, future scientists and their mentors who are faithful participants of the Meeting of Young Chemists of the Ružička Days conference. Enjoy the extremely interesting scientific and professional papers contained in these Proceedings, until the next 20th jubilee of Ružička Days in 2024! We are looking forward to meeting you again in Vukovar! Yours sincerely, Chief Editors Jurislav Babić Vesna Ocelić Bulatović Dajana Kučić Grgić

A novel oxa-aza macrocycle 1R (1R = 1, 6, 20, 25-tetraaza-2, 5:8, 9:17, 18:21, 24:27, 28:36, 37- hexabenzo-10, 16, 29, 35-tetraoxa-cyclooctatriakonta) was prepared by reduction of previously reported porous Schiff base macrocycle 1 (1 = 1, 6, 20, 25-tetraaza-2, 5:8, 9:17, 18:21, 24:27, 28:36, 37- hexabenzo-10, 16, 29, 35-tetraoxa-cyclooctatriakonta-1, 6, 20, 25-tetraen) using NaBH4. The compound was characterized by FT-IR and NMR spectroscopy. The extractability of metal cation by compounds 1 and 1R indicates that the highest extraction is achieved for Cu2+ (87%) in the case of compound 1 and for Au3+ (100%), Cu2+ (100%) and Fe3+ (100%) in the case of compound 2. The composition of extracted species in case of 1R and Cu2+ is 1:1 (ligand: metal ratio, Kex = 11.062), and 1:1 ratio for 1R and Ag+ and Au3+(Kex = 8.7107 and 17.667, respectively).

Metalni ioni mogu se vezati unutar ( endo) ili izvan (egzo) šupljine makrocikla, što najviše ovisi ofleksibilnosti molekule, veličini šupljina te o obliku makrocikličkog liganda [1]. U prethodnimistraživanjima je otkriveno da određena razina dizajniranja liganda za pripravu egzo-koordiniranihspojeva može postići prisustvom rigidne C=N veze koja je u blizini aromatskog sustava [2].Egzo-koordinirani makrociklički spojevi su dosta neuobičajeni, ali mogu biti zanimljivi za istraživanje, zbog svoje izvanredne strukturne raznolikosti i potencijalnog stvaranja 3D poroznih struktura. Egzo-koordinirani kompleksi s makrociklima se najčešće pripravljaju supstitucijom liganda u postojećiendo-makrociklički kompleks ili primjenom specifično dizajniranih makrocikličkih liganada. Anioni mogu biti ključan čimbenik u stvaranju kompleksnih spojeva, kao i u konačnom topološkom oblikuegzo-koordiniranih makrocikličkih spojeva. Otkriveno je da za srebrove(I) oksa-tia makrocikličke koordinacijske spojeve, odabir određenog aniona može uzrokovati stvaranje egzo-koordiniranih (PF6– anion) i endo-koordiniranih (ClO4– anion) kompleksnih spojeva [3]. Priprava kompleksa izvedena je uz odgovarajući ligand L (L = 1, 5-diaza-2, 4:7, 8:16, 17-tribenzo-9, 15-dioksa- ciklooktadeka-1, 5-dien) i srebrovu sol (AgX ; X=ClO4–, PF6–, SbF6– and BF4–) u U-cijevi uz diklormetani metanol kao otapalo, dok je kao barijera između dva otapala korišten kloroform. Uspješno su riješene 4 nove kristalne strukture. Dobiveni spojevi su karakterizirani IR spektroskopijom (FTIR), elementarnom i termičkom analizom te rendgenskom difrakcijom.

Removal of highly toxic air, water and soil pollutants from the environment is a major scientific topic. Macrocycles are organic compounds that can bind toxic species and be designed for extraction of specific metal cations [1, 2. Macrocycles containing oxygen and nitrogen donor atoms in the inner macrocyclic ring (oxa-aza macrocycles) have been studied for that purpose [1. The affinity of an oxa-aza macrocycle towards specific cations can be designed by changing several factors: ring size (cavity size), HSAB principle, donor atom properties, planarity of the system (puckering) and orientation of donor atoms (exodentate or endodentate) [1, 2. In this work we have synthesized a novel N4O4 -donor macrocycle (2) by reduction of previously prepared [2 porous macrocyclic Schiff base (1). Compounds were characterized by elemental and thermal analysis, FT-IR and NMR spectroscopy. Picrate extraction studies were performed following modified Pedersen’s procedure [3 for Ni2+, Cd2+, Zn2+, Ag+, Co2+, Hg2+, Cu2+, Fe3+, Mn3+, Au3+ and Cr3+. The composition of extracted species and extraction constant (Kex) were calculated using dependance of the distribution ratio (D) on macrocycle concentration (logD-logL plot) for Cu2+, Au3+ and Ag+. Metal extraction experiments indicate that highest extraction is achieved for Cu2+ (87%) in the case of compound 1 and for Au3+ (100%), Cu2+ (100%) and Fe3+ (100%) in the case of compound 2. The composition of extracted species in case of 1 and Cu2+ is 1:1 (ligand:metal ratio, Kex = 11.062), and 1:1 ratio for 2 and Ag+ and Au3+ (Kex = 8.7107 and 17.667, respectively).

Porous macrocycles are very interesting among the researchers in last years, mainly because of their potential applications in environmental sustainability. These materials can be classified as organic zeolites. Most of the investigations in this particular research area are based on the shape-persistent macrocycles that have a noncollapsible backbone and a well-defined inner void in the size range from less than 1 up to several nanometers [1]. Because of their rigid structure, organic zeolites have potential application as host materials. Furthermore, the size of voids can be rationally designed by utilization of supramolecular forces or by simple increase or decrease of a number of atoms in the macrocyclic ring [2]. The promising field of research in this area are macrocyclic Schiff bases that can be relatively easily synthesized by simple condensation reactions of suitable formyl and amino precursors. Among these materials, there is a great interest in macrocycles that can form porous structures and subsequently bind gaseous species [3]. This paper addresses synthetic procedures for obtaining a macrocyclic Schiff base, essentially built from dialdehyde and diamine precursors with included gases such as ammonia, sulfur dioxide, and chlorine. In this, presentation we report synthesis and crystallization of a large macrocyclic Schiff base, derived from p-phenylendiamine and 2-[5-(2- formylphenoxy)pentoxy]benzaldehyde. The compound was treated with ammonia, chlorine and sulfur dioxide vapors inside a sealed chamber for 3 hours to form a host-guest complex with those gases. The crystal and molecular structure of gas included compounds was determined by single-crystal X-ray analysis. The amount of absorbed gases was determined by TGA. In addition, the guest-free compound and gas loaded compound were characterized by FTIR to verify the stability of the organic framework.

Hydrazide derivatives of dipicolinic acid contain a large number of potential donor atoms which are capable of coordinating to the metal center in diverse arrangements [1]. Previous studies have shown that Zn dipicolinic acid complexes exhibit effective insulin-mimetic activity [2]. The main goal of this study was to examine the effect of three different inert electrolytes (LiCl, KNO3 and KCl) on the oxido- reduction properties of zinc complex with dipicolinic acid hydrazide derivative (Zn2L2), with two voltammetric techniques (cyclic and differential pulse voltammetry). The measurements were performed using the three electrode system which included a working glassy carbon electrode, counter electrode platinum wire and Ag/AgCl reference electrode. Before each measurement, the surface of the working electrode was polished with α-Al2O3 suspension. The system was purged with high purity argon Ar 5 (φAr = 99.999 %) to accomplish the inert atmosphere. Cyclic voltammograms of the studied zinc complex showed one oxidation peak in all three investigated electrolytes indicating an irreversible oxidation process. The oxidation peak current increased with the increase of scan rate and the highest oxidation peak current was observed for KCl. Differential pulse voltammograms also revealed one oxidation peak, in all three electrolytes. The oxidation peak decreased with successive scans, which confirmes adsorption of the zinc complex oxidation product on the surface of the glassy carbon electrode.

Studies of structural features of polynuclear metal carboxylate complexes (known as “basic carboxylates”) is gaining a lot of attention recently because of their interesting magnetic and electronic properties. These compounds display different magnetic properties (ferro-, ferri-, antiferromagnetic), depending upon molecular and crystal structure. They can also be used as precursors for the synthesis of higher nuclearity clusters. In this work, polynuclear complex with Cu(II), Fe(III) and Cr(III) were synthesized by reactions of acetic and benzoic acid with appropriate metal salts in presence of template molecules (hexamine and guanidine) at room temperature. Prepared complex compounds were characterized by the single crystal X-ray diffraction (sc-XRD), FT- IR spectroscopy and elemental analysis. Under these conditions crystals of two novel polynuclear (Fe(III) and Cu(II)) complexes were obtained and characterized by sc-XRD (FeHEXOK and CuGUABA). X-ray structure analysis of FeHEXOK has shown that compound crystallize in the orthorhombic crystal system, P nma space group (Z=4). The complex compound is comprised of one Fe-basic acetate unit (trinuclear), a non-coordinated nitrate anion, hexamine molecule, and water of crystallization molecules. The positive charge of central Fe- basic acetate unit is neutralized by presence of nitrate anion in the crystal structure and the formal oxidation state of all three iron atoms is +3 (d5 configuration). In the crystal structure, the molecules are primarily linked via strong O‒H∙∙∙N and O‒H∙∙∙O hydrogen bond interactions. X-ray structure analysis of CuGUABA has shown that compound crystallize in the triclinic crystal system, P -1 space group (Z=2). Interestingly, in the crystal structure of CuGUABA there are several different dinuclear Cu-benzoate moieties. The molecular structure of discrete moieties is typical paddle-wheel structure, often observed in Cu- carboxylate complexes. Results of FT-IR spectroscopy and elemental analysis are in agreement with proposed structures. Several other Cr(III), Cu(II) and Fe(III) complexes were synthesized and characterized by FT-IR and elemental analysis.

Over the last couple of decades the oxa-aza macrocycles have been extensively studied due to possible application as selective separating agents for toxic metal cations, chemical sensors and other application. The affinity of macrocyclic system for metal cation can be manipulated by several designable structural factors such as ; cavity size, conformation of donor atoms, flexibility of system, orientation of the potential donor atoms, torsion angles associated with these atoms, distances between donor atoms etc. There are several synthetic strategies for preparation of oxa-aza macrocycles, among them cyclocondenzation reaction of poly-amine and poly-aldehyde precursors resulting in a formation poly-imine compounds was found to be especially convenient. In our work we have developed relatively simple and efficient method for preparation of oxa-aza imine macrocycles by [1+1] and [2+2] cyclocondenzation reactions and efficient method for reduction of poly-imine macrocycles to poly-amine macrocycles. Crystal and molecular structures of prepared compounds were determined and the above mentioned structural factors were correlated with different properties such as metal ion extraction capabilities.

The oxa-aza macrocycles have been extensively studied due to their possible application as selective separating agents for toxic metal cations, chemical sensors and other. The affinity of macrocyclic system towards specific metal cation is governed by several tunable factors such as: ring size (cavity size), HSAB principle, conformation of donor atoms, flexibility of system etc. The poly-imine macrocycles are known to be rigid systems, due to the presence of C=N bond, and subsequently can be reduced to more flexible secondary amine by several different reduction agents (NaBH4, NaBH3CN, NaBH(OAc)3, H2). The reduction of an imine macrocycle to secondary amine macrocycle has been extensively used as intermediate step in preparation of pendant macrocycles, cryptands and spherands. Prior to this study we have developed relatively simple and efficient method for the preparation of 17- to 20-membered oxa-aza imine macrocycles by [1+1] cyclocondenzation reactions of appropriate dialdehydes and diamines. The obtained macrocycles were used as a starting material for the preparation of secondary amine analogues by NaBH4 reduction. The characterization of compounds was done by NMR and IR spectroscopy, elemental analysis and suitable crystals of 18-membered macrocycle were used for single crystal X-ray analysis. The results indicate significant changes in overall conformation of all synthesized macrocycles.

This paper present synthetic procedures to obtain two new mixed ligands coordination compounds with potential pharmacological effects of insulin-mimetic activity. Complex molecules contain biologically important metal ions, Co(III) or Cr(III), multidentate dipicolinic acid hydrazide as primary ligand and diaminohexane as co-ligand. The physico- chemical properties of complex compounds were characterized by IR spectroscopy, thermal analysis (DT-TGA), single crystal X-ray crystallography and cyclic voltammetry. Both complexes crystallize in C 2/c monoclinic space group and have a similar coordination sphere. The metal M(III) ion is coordinated by two tridentate dipicolinate dianions in a distorted [M(N2O)2] octahedral geometry. These mixed ligand chelate complexes are isomorphs and contain metal ion coordinated by two deprotonated hydrazide nitrogen atoms and two oxygen atoms in equatorial plane. The axial coordination sites are occupied by two pyridyl nitrogen atoms. In the crystal structure of both complexes, the molecules are stabilized by intricate pattern of O‒H∙∙∙O, N‒H∙∙∙O and N‒ H∙∙∙Cl hydrogen bond interactions which form an infinite three-dimensional supramolecular network. The hexanediamine cations connect two discrete complex compound molecules via strong N‒H∙∙∙O hydrogen bonds, approximately along -101 crystallographic directions. Thus connected molecules create supramolecular zig- zag motif. The zig-zag structure is additionally stabilized by a series of N‒H∙∙∙Cl interactions that involve chlorine anion, hexanediamine cation and uncoordinated hydrazine nitrogen atom. Interestingly, crystal packing arrangement of CrL is almost identical as in CoL with some minor differences in hydrogen bond geometry. We can conclude based on the X- ray crystallography results that the presence of different metal cation (Cr(III)) in this type of coordination compounds has an almost insignificant impact on crystal structure and molecular stereochemistry. The crystal packing design is driven by the presence of uncoordinated species in the crystal structure, like as, solvent molecules hexanediamine cation, water molecule and chlorine anion, which is well supported by hydrogen bonds pattering. The results of IR spectroscopy, thermal analysis and cyclic voltammetry are in a good agreement with crystal structure determination.

Konstruiran je cjenovno povoljan čvrsti anionski tenzidni senzor visoke osjetljivosti uz dodatak ionskog para, višestjenčanih ugljikovih nanocjevčica (MWCNT) i jeftine grafitne mine iz olovke kao nosioca senzorskog sloja. Tenzidni senzor je karakteriziran pomoću elektrokemijske impedancijske spektroskopije (EIS) i direktne potenciometrije. EIS mjerenja su pokazala da MWCNT u konstruiranom senzoru smanjuje ohmski otpor i povećava stabilnost i reproducibilnost senzora. Direktnim potenciometrijskim mjerenjima odziva senzora na natrijev dodecilsulfat (SDS) dobiven je Nernstovski nagib, -57, 1 mV ; s područjem linearnosti od 2, 0x10-7 M to 1, 0x10-3 M.Potenciometrijske titracije izvedene su s heksadecil- trimetilamonijevim bromidom kao titrantom te SDS kao analitom rezultirale su dobro definiranim i oštrim točkama infleksije. MWCNT tenzidni senzor je korišten kao indikator završne točke titracije uzoraka otpadnih voda, gdje je s visokom točnošću detektirao koncentracije anionskih tenzida.

The 7th International Scientific and Professional Conference Water for all is organized to honour the World Water Day by the Josip Juraj Strossmayer University of Osijek, European Hygienic Engineering & Design Group (EHEDG), Danube Parks, Croatian Food Agency, Croatian Water, Faculty of Food Technology Osijek, Faculty of Agriculture in Osijek, Faculty of Civil Engineering Osijek, Josip Juraj Strossmayer University of Osijek Department of Biology, Josip Juraj Strossmayer University of Osijek Department of Chemistry, Nature Park “Kopački rit”, Osijek- Baranja County, Public Health Institute of the Osijek- Baranja County and „Vodovod-Osijek“ -water supply company in Osijek. The topic of World Water Day 2017 was "Wastewater" emphasizing the importance and influence of wastewater treatments on global environment. The international scientific and professional conference Water for all is a gathering of scientists and experts in the field of water management, including chemists, biologists, civil and agriculture engineers, with a goal to remind people about the significance of fresh water and to promote an interdisciplinary approach and sustainability for fresh water resource management. The Conference has been held since 2011. About 300 scientists and engineers submitted 95 abstracts to the 7th International Scientific and Professional Conference Water for all, out of which 33 was presented orally and 62 as posters. 47 full papers were accepted by the Scientific Committee. 38 full papers became the part of the this Proceedings while 9 papers were accepted for publication in Croatian Journal of Food Science and Technology and Electronic Journal of the Faculty of Civil Engineering Osijek - e-GFOS.

Dijabetes je kronična bolest često uzrokovana "modernim načinom života", koji podrazumijeva nezdravu prehranu, nedovoljno fizičkog kretanja te je kataliziran stresom. Adultni ili stečeni dijabetes (dijabetes tipa 2) ne može se izliječiti, ali se kontrolira peroralnim lijekovima na bazi dipikolinskih kompleksa. Ranijim istraživanjima dokazano je da dipikolinski kompleksni spojevi s prijelaznim metalima snižavaju visoku razinu šećera u krvi i vraćaju osjetljivost inzulinskim receptorima [1, 2]. Pripremljeni su kompleksni spojevi derivata dipikolinske kiseline, 6-(2- benzoilhidrazinkarbonil)-pikolinska kiselina, s odabranim prijelaznim metalima i diaminoheksanom u svrhu određivanja njihove strukture i fizikalnokemijskih svojstava. Priprava kompleksnih spojeva izvedena je na sobnoj ili povišenoj temperaturi u metanolu kao otapalu. Sintetiziranim spojevima predložena je molekulska struktura pomoću spektroskopske (FTIR) i termičke (TG-DSC) analize. Apsorpcijske vrpce IR spektara dobivenih kompleksnih spojeva, u usporedbi sa spektrom čistog benzhidrazidodipikolinatnog liganda, pokazuju značajne pomake u odnosu na nekoordinirani ligand što upućuje na kelatno vezivanje metala s deprotoniranim ligandom. Termogravimetrijskom analizom određen je eksperimentalni udio metala u dobivenim kompleksima koji, uz manja odstupanja, odgovara teorijski pretpostavljenim strukturama. Dobiveni koordinacijski spojevi pripadaju skupini spojeva koji imaju potencijalna inzulinomimetička svojstva te se mogu koristiti u daljnjim istraživanjima u razvoju antidijabetskog lijeka.

Ruralni turizam jednajeod najpopularnijih strategijaza razvoj ruralnih i zapostavljenih prostora te oživljenje tradicionalnih industrijakao što su poljoprivreda i stočarstvo. Dalmatinska zagora ruralnije dio južnohrvatske regijeDalmacije iodnosi se na unutrašnjost Splitsko-dalmatinske županije. Premda je Dalmatinska zagora područje velikogaturističkog potencijala, organizirana turistička djelatnost nalazi se u samim začecima. Budući da su, sukladno modelu integriranogarazvoja ruralnogaturizma, suradnja i umrežavanje dionika preduvjeti održivogaturističkog razvoja ruralnih područja, u ovomse radu istražujerazina uključenostii povezanosti predstavnika javnoga, privatnogai civilnogasektorau postupku razvojaruralnogaturizma Dalmatinske zagore. U svrhu ovogaistraživanja, prikupljeni su podaci o broju dolazaka i noćenja, broju registriranih turističkih objekata i kreveta (prema vrsti smještaja i broju zvjezdica), godišnjem prihodu turističkih zajednica, broju značajnijih investicija javnogasektora u turističku infrastrukturu, te broju poduzetničkih pothvata, sve u razdoblju od 2011. do 2015. godine. Također, dvjema zasebnim e- anketama prikupljeni supodaci o predodžbama lokalnih stanovnika odnosno drugihdionika o stanjururalnogaturizmaDalmatinske zagore. Rezultati jasno ukazuju da je Dalmatinska zagora tek na pragu drugeod četiri etape integriranogarazvoja ruralnogaturizma. U konačnici, ovajradpružasmjerniceza buduće integrirane razvojne scenarijeu ruralnom prostoru južne Hrvatske.

Dalmatinska zagora kontinentalni je odnosno zaobalni dio srednje Dalmacije, a u slučaju ovog specijalističkog poslijediplomskog rada odnosi se na dio Dalmatinske zagore unutar Splitsko-dalmatinske županije. Dalmatinska zagora područje je velikog turističkog potencijala, ali i relativno niskog stupnja turističke razvijenosti. Organizirana turistička djelatnost nalazi se u samim začecima. Ovaj specijalistički poslijediplomski rad bavi se ulogom ključnih dionika u razvoju ruralnog turizma Dalmatinske zagore i istražuje ulogu predstavnika javnog, privatnog i civilnog sektoru u ovom razvojnom procesu. Model integriranog ruralnog turizma (IRT) odnosi se na uvezivanje i umrežavanje navedenih dionika (predstavnika javnih tijela, poduzetnika i stanovnika) s ciljem što efikasnijeg razvoja turizma u ruralnim područjima. Ovakav pristup podrazumijeva snažnu uključenost lokalnih zajednica, partnerstvo svih dionika te potpuno strukturirane razvojne procese. Rad obrađuje domaću i stranu stručnu literaturu iz područja ruralnog turizma, kao i primjere iz prakse iz razvijenih i manje razvijenih ruralnih turističkih destinacija. Namjera ovog specijalističkog poslijediplomskog rada bila je dokazati kako razvoj ruralnog turizma stvara socio-ekonomsku korist lokalnoj zajednici odnosno lokalnom stanovništvu. Drugi dio bavi se istraživanjem percepcije Dalmatinske zagore kao turističke destinacije kod lokalnog stanovništva, istraživanjem međusobnog odnosa pojedinih dionika u ruralnom turizmu te njihovom percepcijom međusobne odgovornosti za razvoj turizma. Konačni cilj ovog specijalističkog poslijediplomskog rada trasiranje je smjernica za buduće integrirane razvojne scenarije u ruralnom prostoru Dalmatinske zagore. Dalmatian Hinterland is the continental inland region located in Central Dalmatia, and in the case of this particular postgraduate thesis refers to the part of Dalmatian Hinterland within the Split-Dalmatia County. Dalmatian Hinterland is an area containing great tourist potential, as well as currently being relatively touristically low-developed. Organized tourist activity in the area is only starting. This specialist postgraduate thesis deals with the role of key actors in the development of rural tourism in Dalmatian Hinterland, while exploring the role of the representatives of the public, private and civil sectors in this developmental process. The integrated rural tourism model (IRT) refers to the binding and networking between the aforementioned participants (the representatives of the public, businesspeople and citizens) with the aim of a more efficient tourism development in rural areas. This approach implies a strong involvement of local communities, a partnership between all participants and completely structured developmental processes. This thesis explores the local and foreign literature dealing with the topic of rural tourism, as well as practical examples from well and less-developed rural tourist destinations. The goal of this specialist postgraduate thesis was to prove how the development of rural tourism creates a socio-economic benefit for the local community, that is to say local citizens. The second part of the thesis researches the perception of Dalmatian Hinterland as a tourist destination within the local community, the relationship between individual actors in rural tourism and their perception of mutual responsibility when it comes to tourist development. The final aim of this specialist postgraduate thesis is to map the guidelines for future integrated developmental scenarios in the rural area of Dalmatian Hinterland.

A low-cost, high sensitive solid contact tenside sensors with ion-pair, multi walled carbon nanotubes (MWCNTs) and low-cost graphite pencil lead (as a sensor layer carrier), were fabricated. The MWCNT nanomaterials were used to increase the active surface, to reduce the membrane resistance and to reduce the signal- to-noise ratio. The sensor was characterised by electrochemical impedance spectroscopy (EIS) and direct potentiometry.

Kinurenska kiselina naziv je za 4- hidroksikinolin-2-karboksilnu kiselinu koja nastaje kao metabolit L-triptofana u organizmu tzv. kinurenskim metaboličkim putem. Čak 95% triptofana u središnjem živčanom sustavu razgrađuje se ovim putem, a nastali produkti, kao što je kinurenska kiselina, djeluju kao antagonisti neuroreceptora. Na NMDA (N-metil-D- aspartat) receptor se vežu glutamat i glicin kao agonisti i tako omogućuju slobodan protok kationima kroz staničnu membranu neurona. Kinurenska kiselina djeluje kao antagonist vežući se na glicinsko mjesto u navedenom receptoru te tako utječe na neurotransmisijske procese [1]. Često se koncentracije kinurenske kiseline mjere keliranjem s cinkom pri čemu nastaje fluorescentni kompleks [2]. U ovom radu istražene su reakcije kinurenske kiseline s kationima cinka tako što su pripravljene serije otopina kinurenske kiseline i cinkova acetata u vodi pri određenim pH vrijednostima. Dobiveni su spojevi okarakterizirani infracrvenom spektroskopijom i termogravimetrijskom analizom. Predložene su strukture spojeva na temelju dobivenih rezultata.

Oxido-reduction properties of a novel synthesized Schiff base were studied by cyclic and differential pulse voltammetry. The results of electrochemical study have shown that the oxidation of the investigated Schiff base is reversible, diffusion controlled process and that the oxidation products are adsorbed on the glassy carbon electrode surface.

Ispitivana su oksido-redukcijska svojstva novosintetizirane Schiffove baze uporabom cikličke i diferencijalne pulsne voltametrije. Mjerenja su izvedena u troelektrodnoj ćeliji u nevodenom mediju pri sobnoj temperaturi, a inertna atmosfera je postignuta propuhivanjem sustava argonom visoke čistoće Ar 5 (Ar = 99, 999 %), prije svakog mjerenja. Kao radna elektroda korištena je elektroda od staklastog ugljika, protuelektroda je bila platinska žica, a kao referentna elektroda je korištena Ag/Ag+ elektroda za nevodeni medij. Rezultati cikličke voltametrije su pokazali da se ispitivana Schiffova baza oksidira (uočen je jedan oksidacijski strujni vrh u anodnom dijelu voltamograma na potencijalu Ep, a = 0, 677 V, a visina oksidacijskog strujnog vrha raste s povećanjem koncentracije (c = 1, 9 ·10-4 mol dm-3 - 6, 1 ·10-4 mol dm-3 ) i brzine promjene potencijala (ν = 50-300 mV/s). Diferencijalnom pulsnom voltametrijom je također uočen jedan oksidacijski strujni vrh pri Ep, a = 0, 65 V, koji se povećavao s povećanjem koncentracije ispitivane Schiffove baze.

Oxido-reduction properties of a newly synthesized Schiff base were investigated by cyclic voltammetry and differential pulse voltammetry. Measurements were conducted in a three electrode voltammetric cell in a non- aqueous media. Glassy carbon was used as a working electrode, platinum wire as counter electrode and non-aqueous Ag/Ag+ electrode as a reference electrode. Inert atmosphere was acomplished by system purging with high purity argon Ar 5 [(fi)Ar = 99, 999 %], before each measurement. Cyclyc voltammograms revealed one oxidation peak of the investigated Schiff base (Ep, a = 0.69 V), which increased with increasing concentration (c = 3.1 •10-5 mol dm- 3... 1.25 •10-4 mol dm-3) and scan rate (ν = 50...300 mV/s). Differential pulse voltammetry showed one oxidation peak Ep, a = 0, 69 V, which also increased with increasing concentration.

Oxido-reduction properties of a newly synthesized Schiff base were investigated by cyclic voltammetry and differential pulse voltammetry. Measurements were conducted in a three electrode voltammetric cell in a non- aqueous media. Glassy carbon was used as a working electrode, platinum wire as counter electrode and non-aqueous Ag/Ag+ electrode as a reference electrode. Inert atmosphere was acomplished by system purging with high purity argon Ar 5 (Ar = 99, 999 %), before each measurement. Cyclyc voltammograms revealed one oxidation and one reduction peak of the investigated Schiff base (Ep, a = 0, 44 V and Ep, k = 0, 39 V), which both increased with increasing concentration (c = 3, 1 •10-5 mol dm-3... 1, 25 •10-4 mol dm-3) and scan rate (ν = 50...300 mV/s) [1] [2]. Differential pulse voltammetry showed one oxidation peak Ep, a = 0, 41 V, which also increased with increasing concentration [3].

There is a great interest in macrocycles that can form open tubular structures. These materials can be classified as organic zeolites. Most of the investigations in this particular research area are based on the shape-persistent macrocycles that have a noncollapsible backbone and a well defined inner void in the size range from less than 1 up to several nanometers [1]. Because of their rigid structure, organic zeolites have potential application as host materials. Furthermore, size of voids can be rationally designed by utilization of supramolecular forces or by simple increase or decrease of number of atoms in the macrocyclic ring. The promising field of research in this area are macrocyclic Schiff bases that can be relatively easily synthesized by simple condensation reactions of suitable formyl and amino precursors. There are several examples of these types of compounds with selective uptake of gaseous species [2]. This paper addresses synthetic procedures for obtaining a macrocyclic Schiff base, essentially built from dialdehyde and diamine precursors and host-guest interactions with iodine vapors. In this paper we report synthesis of a large macrocyclic Schiff base, derived from p-phenylendiamine and 2-[5-(2-formylphenoxy)pentoxy]benzaldehyde. The crystal and molecular structure of the compound was determinated by single crystal X-ray analysis. The molecule crystallizes in the monoclinic crystal system, P 21/c space group. In the crystal, the molecules are linked with very weak C-H•••N interactions along the a-axis, thereby forming a tubular structure. The derived compound is a large macrocyclic Schiff base with 38 atoms in the inner macrocyclic ring and a well-defined inner void of 441, 8 Å3. Also, the diagonal distances between donor atoms are around 1.3 nm. Therefore, this compound can be considered as a nano-tubular material. In addition, we have studied absorption of iodine vapors inside the tubular voids. The compound was treated with iodine vapors inside a sealed chamber for 24 hours to form a host-guest complex with iodine. Small amount of solid material (around 10 mg) was subsequently treated with ethanol to remove iodine species on the crystal surface and the amount of absorbed iodine was determined by TGA. The host: guest ratio was found to be approximately 2:1. In addition, the guest-free compound and iodine-loaded compound were characterized by FTIR and Raman spectroscopy in order to verify the stability of organic framework.