Laboratório de Microbiologia.

Laboratório de Microbiologia.info:eu-repo/semantics/publishedVersio

Cyanide and fluoride colorimetric sensing by novel imidazo-anthraquinones functionalized with indole and carbazole

Novel imidazo-anthraquinones functionalized with indole and carbazole have been synthesised and characterised and their evaluation as colorimetric chemosensors was carried out in acetonitrile as well as in acetonitrile/H2O (97:3) in the presence of several anions such as F-, Cl-, Br-, I-, CN-, NO3-, ClO4-, AcO-, BzO-, NO3-, ClO4-, HSO4- and H2PO4-. Additionally, their behaviour in the presence of H+ and OH- was also studied. Upon addition of CN- and F− to acetonitrile solutions of compounds 1-3, a marked colour change from yellow to orange was observed and the fluorescence emission of 1 and 2 was switched “on”. The recognition in organic aqueous solution lead to the selective and sensitive naked-eye detection (mM) of CN- for all receptors, with an easily detectable colour change from yellow to orange. The binding stoichiometry between the receptors and the anions was found to be 2:1. The binding process was also followed by 1H NMR titrations showing that two different binding modes occurred in the presence of fluoride or cyanide anions, which is in agreement with the spectrophotometric titrations.Fundação para a Ciência e a Tecnologia (FCT

Synthesis of new fluorescent 2-(2’, 2’’-bithienyl)-1,3-benzothiazoles

Bithienyl-1,3-benzothiazole derivatives were synthesised by reacting various 5-formyl-5’-alkoxy- or 5-formyl-5’-N,N-dialkylamino-2,2’-bithiophenes with ortho-aminobenzenethiol in good to excellent yields. Evaluation of the fluorescence properties of these compounds was carried out. They show strong fluorescence in the 450-600 nm region, as well as high quantum yields and large Stokes’ shifts.Fundação para a Ciência e Tecnologia

Batch culture growth of Chlorella zofingiensis on effluent derived from two-stage anaerobic digestion of two-phase olive mill solid waste

This paper presents the use of an effluent derived from two-stage anaerobic digestion of two-phase olive mill solid waste (OMSW) as a substrate for the production of Chlorella zofingiensis in batch mode. Chlorella zofingiensis when grown autotrophycally can accumulate significant quantities of valuable carotenoids which are used as an additive in fish and poultry farming, as colorants in foods and in health care products. It was found that two-phase OMSW previously treated by two-stage anaerobic digestion and further sterilized may be used as a culture medium for the microalgae Chlorella zofingiensis. Typical growth curves were obtained using both the above-mentioned anaerobic effluent and a synthetic medium. Total chemical oxygen demand (TCOD) and soluble chemical oxygen demand (SCOD) removals of 37% and 45% respectively were achieved in batch experiments after 11 days' operation time. The specific growth rate was lower when the treated effluent was used as the feed substrate (0.02 h-1) in comparison to the synthetic medium (0.03 h-1). The specific growth rates of the exponential phases were determined by using a first-order kinetic model applied to chlorophyll a (C a ) and total chlorophyll (TC) concentrations, as indirect measurements of the microalgae concentration. It was concluded that the effluent from two-stage anaerobic digestion of two-phase OMSW constituted an appropriate culture medium for the growth of Chlorella zofingiensis, providing a simple technology feasible for producing a very useful product for animal feeding

Synthesis and evaluation of fluorimetric and colorimetric chemosensors for anions based on (oligo)thienyl-thiosemicarbazones

A family of heterocyclic thiosemicarbazone dyes (3a-d) containing thienyl groups has been synthesized, characterized and their chromo-fluorogenic response in acetonitrile in the presence of selected anions studied. Acetonitrile solutions of 3a-d show absorption bands in the 338-425 nm range which are modulated by the groups attached to the thiosemicarbazone moiety. The fluoride, chloride, bromide, iodide, dihydrogen phosphate, hydrogen sulfate, nitrate, acetate and anions were used in the recognition studies. Only sensing features were observed for fluoride, cyanide, acetate and dihydrogen phosphate anions. Two different chromogenic responses were found, (i) a small shift of the absorption band due to coordination of the anions with the thiourea protons and (ii) the appearance of a new red shifted band due to deprotonation of the receptor. For the latter process changes in the color solutions from pale-yellow to orange-red were observed. Fluorescence studies showed a different emission behavior according to the number of thienyl rings in the π-conjugated bridges. Stability constants for the two processes (complex formation + deprotonation) for receptors 3a-d in the presence of fluoride and acetate anions were determined from spectrophotometric titrations using the HypSpec program. The interaction of 3d with fluoride was also studied through 1H NMR titrations. Semiempirical calculations to evaluate the hydrogen-donating ability of the receptors were also performed.Fundação para a Ciência e a Tecnologia (FCT) , Acções Integradas Luso-Espanholas/CRUP, Generalitat Valenci

Novel functionalised imidazo-benzocrown ethers bearing a thiophene spacer as fluorimetric chemosensors for metal ion detection

Novel phenylalanine derivatives bearing benzimidazole and crown ethers as coordinating/reporting units and thiophene as a spacer unit were synthesized for the first time, and their evaluation as fluorimetric chemosensors was carried out in acetonitrile and acetonitrile/water solutions. 15-Crown-5 benzimidazolyl phenylalanine methyl ester, 15-crown-5 thienylbenzimidazolyl phenylalanine methyl ester and 18-crown-6 thienylbenzimidazolyl phenylalanine methyl ester were tested for alkaline, alkaline-earth and transition metal ions (such as Na+, Ca2+, Cd2+, Co2+, Cr3+, Cu2+, Fe2+, Fe3+, Hg2+, Ni2+, Pd2+ and Zn2+). The different crown ether binding moieties as well as the electronic nature and the length of the π-bridge linked to the benzimidazole heterocycle allowed the fine tuning of the sensory properties as seen by spectrofluorimetric titrations. Therefore, 15-crown-5 benzimidazolyl phenylalanine methyl ester is a fluorimetric chemosensor, being selective and sensitive for Cu2+ and Pd2+ in aqueous solutions (ACN/H2O; 80:20). On the other hand, the metal cation sensing properties displayed by 15-crown-5 thienylbenzimidazolyl phenylalanine methyl ester bearing an arylthienyl spacer showed that this is a promising candidate as fluorimetric chemosensor for Fe3+, Pb2+ and Pd2+ in acetonitrile solution.Thanks are due to Fundação para a Ciência e Tecnologia (Portugal) for financial support to the Portuguese NMR network (PTNMR, Bruker Avance III 400-Univ. Minho), FCT and FEDER (European Fund for Regional Development)-COMPETEQREN-EU for financial support to the research centre CQ/UM [PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302], a PhD grant to C.I.C. Esteves (SFRH/BD/68360/2010) and a post-doctoral grant to R.M.F. Batista (SFRH/BPD/79333/2011).info:eu-repo/semantics/publishedVersio