In previous studies of our research group, we have selectively generated a pool of new 4-thiazolidinones by three-component reaction, solvent-free and microwave-assisted, between an aldehyde derived from a carbohydrate, a heteroaromatic amine and thioglycolic acid.[i] More recently, we have studied the effect of the addition of a boron organocatalyst on the selective synthesis of a novel under the same reaction conditions.[ii] With the aim of exploring the best reaction conditions for the diastereoselective synthesis of the 1,4-thiazepan-3-ones and 4-thiazolidinones , we have studied not only the effect on solvent variation but also the aggregation of AlCl₃ or different zeolites as Lewis acid catalysts (mordenita, zeolite 13x and ZSM-5).

The generation of the corresponding intermediates and reaction products were monitored by CG-MS, taking reaction aliquots every five minutes of reaction. The characterization of the intermediates and corresponding reaction products were performed by NMR spectroscopy.

[i] Ocampo, R. A.; Quiroga, A. A.; Koll, L. C; Fascio, M.; D´accorso, N. B. Síntesis y caracterización de 4-tiazolidinonas unidas a heterociclos nitrogenados y sustituidas por un carbohidrato adecuadamente funcionalizado. XX Simposio Nacional de Química Orgánica. Argentina. Buenos Aires. 2015.

[ii] Ocampo, R. A.; Quiroga, A. A.; D´accorso, N. B. Estudio de la síntesis estereo y diasteroselectiva de una nueva 1,4-tiazepan-3-ona sustituida por un hidrato de carbono utilizando irradiacion de microondas. XX Simposio Nacional de Química Orgánica. Argentina. Buenos Aires. 2017.

Preliminary phytochemical screening of the extracts revealed the presence of Carbohydrates, Steroids, Proteins, amino acids alkaloids, flavonoids, glycosides and tannins. The presence of these bioactive constituents is associated with the antimicrobial activity of the plant. The seed extract of Cucurbita pepo dissolved in alcoholic and hydroalcoholic solution showed the spectrum of inhibition on, Bacillus subtilis, and Escherichia coli by Cylinder plate method. The observations revealed significant zone of inhibition and supports to antibacterial activity.

The work reports facile green protocol for synthesis of novel ten derivatives of diethyl ((4-oxo-4H-chromen-3-yl)((5-sustituted phenyl-1,3,4-thiadiazol-2-yl)amino)methyl) phosphonate 6(a-j). The derivatives 6(a-j) were synthesized under ultrasound by coupling substituted thiadiazoles, α-aminophosphonate derivatives and 3-formyl chromone in a one-pot three component Kabachnik-Fields reaction, in presence of zirconium oxychloride (ZrOCl₂) as a catalyst, to give the final compounds in neat and clean protocol giving better yields in shorter reaction time. Thiadiazole and its derivatives possess a broad range of biological and pharmacological properties. 5-substituted phenyl-1,3,4-thiadiazol-2-amine is widely used as starting material for the synthesis of a broad range of heterocyclic compounds and as substrates for drug synthesis. 3-Formylchromone derivatives possess a broad range of biological and pharmacological properties. The α-amino phosphonate derivatives constitute an important class of organophosphorus compounds on account of their versatile biological activity. Nowadays, in medicinal chemistry molecular hybridization is an important strategy in planning drug synthesis. The important biological activities associated with these three moieties, namely, substituted thiadiazole, chromones and α-amino phosphonate derivatives promoted us to club these pharmacophores in a single molecule with the hope to get novel coupled derivatives with potent and enhanced biological activity.

The recognition and detection of ionic species has aroused great interest due to their important roles in many biological and environmental processes. Colorimetric chemosensors are molecules that allow naked-eye detection of ionic species without resource to any instrumentation, offering qualitative and quantitative information and are considered as one of the most effective analytical method for environmental monitoring, particularly in the detection of metal ions whose presence in the environment has serious consequences.¹

Research of sensors with good sensitivity and good selectivity in aqueous medium has been of great interest. Chemosensors soluble in aqueous media are very interesting, because of the importance in revealing a number of biological processes, disease states and environmental pollutions.²

Hydrazone derivatives are versatile compounds with several applications such as in medicinal chemistry due to their vast biological activity and as optical (colorimetric and fluorimetric) sensing of anions and metal cations. Other applications in materials science include molecular switches, OLEDs, etc.³

In this communication, we report the synthesis of one hydrazone derivative, functionalized with an heterocyclic moiety, in order to evaluate its photophysical properties and chemosensory ability. The new derivative was characterized by the usual techniques and a detailed photophysical study was undertaken. The evaluation of the novel compound as a colorimetric chemosensor was carried out by performing titrations in acetonitrile and acetonitrile/water in the presence of relevant organic and inorganic anions, and of alkaline, alkaline-earth and transition metal cations.

Acknowledgements: Thank are due to Fundação para a Ciência e Tecnologia (Portugal) and FEDER-COMPETE for financial support through Centro de Química (UID/QUI/00686/2013 and UID/ QUI/0686/2016), and a PhD grant to R.C.M. Ferreira (SFRH/BD/86408/2012). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased with funds from FCT and FEDER.

References:

1. a) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. J. Photochem. Photobiol. A: Chem., 2013, 259, 33. b) Thakur, B.; Amarnath, C. A.; Mangoli, S. H.; Sawant, S. N. Sens. Actuat. B, 2015, 207, 262.
2. a) Patil, S.; Patil, R.; Fegade, U.; Bondhopadhyay, B.; Pete, U.; Suban, K. S.; Singh, N.; Basu, A.; Bendre, R.; Kuwar, A. Photochem. Photobiol. Sci., 2015, 14, 439. b) Udhayakumari, D.; Velmathi, S.; Boobalan, M. S.; Venkatesan, P.; Wu, S.-P. J. Luminescence, 2015, 158, 484. c) Alici, O.; Erdemir, S. Sens. Actuat. B, 2015, 208, 159. d) Hu, Y.; Zhang, J.; Lv, Y.-Z.; Huang, X.-H-; Hu, S.-li. Spectrochim. Acta Part A: Mol. Biomol. Spect., 2016, 157, 164.
3. (a) Raposo, M. M. M.; García-Acosta, B.; Ábalos, T.; Calero; P.; Martínez-Manez, R.; Ros-Lis, J. V.; Soto, J. J. Org. Chem., 2010, 75, 2922. b) Santos-Figueroa, L. E.; Moragues, M. E.; Raposo, M. M. M., Batista, R. M. F.; Ferreira, R. C. M.; Costa, S. P. G.; Sancenón, F.; Martínez-Máñez, R.; Ros-Lis, J. V.; Soto, J. Tetrahedron 2012, 68, 7179-7186. c) Santos-Figueroa, L. E.; Moragues, M. E.; Raposo, M. M. M., Batista, R. M. F.; Ferreira, R. C. M.; Costa, S. P. G.; Sancenón, F.; Martínez-Máñez, R.; Ros-Lis, J. V.; Soto, J. Org. Biomol. Chem. 2012, 10, 7418-7428. d) Marín-Hernández, C.; Santos-Figueroa, L. E.; Sayed S.; Pardo, T.; Raposo, M. M. M., Batista, R. M. F.; Costa, S. P. G.;  Sancenón, F. Martínez-Máñez, R. Dyes Pigments, 2015, 122, 50.

The research on selective chromo-fluorogenic sensors for anions, cations and neutral molecules is an exciting topic with recent developments, especially in the possibility of using colorimetric/fluorimetric probes to sense both anions and cations in aqueous solution. In particular, heterocyclic systems which have the ability to act as the recognition unit as well as the signalling unit, are very interesting since variation of their absorption/fluorescence properties can happen during the recognition event. With careful design, for example by inclusion of additional heterocycles, the analyte recognition and overall photophysical properties can be improved, leading to higher sensitivity and selectivity.¹ Imidazole based chromophores have received increasing attention recently due to their distinctive optical properties and excellent thermal stabilities making them versatile systems for several applications such as optical chemosensors and two-photon absorbing molecules,² among other applications in materials and medicinal chemistry. For the recognition of certain anions, anthraquinone derivatives have been reported as suitable systems for colorimetric sensing since they are an example of electron acceptor groups that can be electronically connected with recognition units.³

Based on the above facts, herein we report the synthesis of one imidazo-anthraquinone, and its photophysical and chemosensory properties. The new derivative was obtained in good yield through a Radziszewski reaction between 1,2-diamino anthraquinone and an heterocyclic aldehyde, characterized by the usual techniques and a detailed photophysical study was undertaken. The evaluation of the compound as a colorimetric chemosensor was carried out by performing spectrophotometric titrations in ACN and ACN/H₂O in the presence of relevant organic and inorganic anions, and of alkaline, alkaline-earth and transition metal cations.

Acknowledgements: Thank are due to Fundação para a Ciência e Tecnologia (Portugal) and FEDER-COMPETE for financial support through Centro de Química (UID/QUI/00686/2013 and UID/ QUI/0686/2016), and a PhD grant to R.C.M. Ferreira (SFRH/BD/86408/2012). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased with funds from FCT and FEDER.

1. a) M. Formica, V. Fusi, L. Giorgi, M. Micheloni, Coord. Chem. Rev., 2012, 256, 170-192. b) J.-F. Xu, H.-H. Chen, Y.-Z. Chen, Z.-J. Li, L.-Z. Wu, C.-H. Tung, Q.-Z. Yang, Sens. Actuators B, 2012, 168, 14-19. c) L. E. Santos-Figueroa, M. E. Moragues, E. Climent, A. Agostini, R. Martínez-Máñez, F. Sancenón, Chem. Soc. Rev., 2013, 42, 3489-3613. d) L. You, D. Zha, E. V. Anslyn, Chem. Rev., 2015, 115, 7840−7892. e) J. Li, S. Chen, P. Zhang, Z. Wang, G. Long, R. Ganguly, Y. Li, Q. Zhang, Chem. Asian J. 2016, 11, 136–140.
2. a) E. Oliveira, R. M. F. Batista, S. P. G. Costa, M. M. M. Raposo, C. Lodeiro, Inorg. Chem., 2010, 49, 10847-10857. b) C. Marín-Hernández, L. E. Santos-Figueroa, S. Sayed, T. Pardo, M. M. M. Raposo, R. M. F. Batista, S. P. G. Costa, F. Sancenón, R. Martínez-Máñez, Dyes Pigments, 2015, 122, 50-58. c) Q. Zhang, X. Tian, Z. Hu, C. Brommesson, J. Wu, H. Zhou, J. Yang, Z. Sun, Y. Tian, K. Uvdal, Dyes Pigments, 2016, 126, 286-295. d) C. I. C. Esteves, M. M. M. Raposo, S. P. G. Costa, Dyes Pigments, 2016, 134, 258-268.
3. a) R. M. F. Batista, E. Oliveira, S. P. G. Costa, C. Lodeiro, M. M. M. Raposo, Org. Lett., 2007, 9, 3201-3204. b) R. M. F. Batista, S. P. G. Costa, M. M. M. Raposo, J. Photochem. Photobiol. Chem., 2013, 259, 33-40. c) R. M. F. Batista, E. Oliveira, S. P. G. Costa, C. Lodeiro, M. M. M. Raposo, Supramol. Chem., 2013, 26, 71-80. d) R. M. F. Batista, S. P. G. Costa, M. M. M. Raposo, Sens. Actuators B: Chem., 2014, 191, 791-799. e) C. Marín-Hernández, L. E. Santos-Figueroa, M. E. Moragues, M. M. M. Raposo, R. M. F. Batista, S. P. G. Costa, T. Pardo, R. Martínez-Máñez, F Sancenón, J. Org. Chem., 2014, 79, 10752-10761.

The phthalazine heterocycle has a highly π-deficient aromatic character that makes it a good candidate to be incorporated as electron acceptor group, or even as spacer with auxiliary electron withdrawing abilities, into push-pull systems. Additionally, offers the possibility of protonation, hydrogen bond formation, and chelation through the nitrogen atoms.¹ 

Phthalazine derivatives have applications as therapeutic agents,² chemiluminescent materials,³ ligands in transition metal catalysis,⁴ and as optical materials.⁵

Some time ago, our research group developed a methodology for the preparation of phthalazine derivatives in three steps, affording halo-thienyl-phthalazine derivatives that play an important role in diazine chemistry since they offer great potential for further functionalization by nucleophilic displacement of the halogen, making numerous otherwise inaccessible diazines become available.⁶

In continuation of the work developed before by our research group,^{4b-c, 6} we report in this communication the synthesis and the evaluation of the optical properties of two novel thienyl-phthalazine derivatives, functionalized with (bi)thiophene moieties, having in mind further functionalization in order to prepare push-pull heterocyclic systems for several optical and photovoltaic applications. These studies showed that the optical properties could be readily tuned by varying the π-conjugation path length through the introduction of a second thiophene unit.

Acknowledgements: Thank are due to Fundação para a Ciência e Tecnologia (Portugal) and FEDER-COMPETE for financial support through Centro de Química (UID/QUI/00686/2013 and UID/ QUI/0686/2016), and a PhD grant to S. S. M. Fernandes (SFRH/BD/87786/2012). The NMR spectrometer Bruker Avance III 400 is part of the National NMR Network and was purchased with funds from FCT and FEDER.

References

1. Achelle, S.; Plé, N.; Turck, A., Incorporation of pyridazine rings in the structure of functionalized π-conjugated materials. RSC Adv. 2011, 1 (3), 364-388.
2. Vila, N.; Besada, P.; Costas, T.; Costas-Lago, M. C.; Terán, C., Phthalazin-1(2H)-one as a remarkable scaffold in drug discovery. Eur. J. Med. Chem. 2015, 97, 462-482.
3. (a) Achelle, S.; Baudequin, C.; Plé, N., Luminescent materials incorporating pyrazine or quinoxaline moieties. Dyes Pigments 2013, 98 (3), 575-600; (b) Yoshida, H.; Ureshino, K.; Ishida, J.; Nohta, H.; Yamaguchi, M., Chemiluminescent properties of some luminol related compounds (II). Dyes Pigments 1999, 41 (3), 177-182; (c) Achelle, S.; Rodríguez-López, J.; Katan, C.; Robin-le Guen, F., Luminescence behavior of protonated methoxy-substituted diazine derivatives: toward white light emission. J. Phys. Chem. C 2016, 120 (47), 26986-26995.
4. (a) Kolb, H. C.; VanNieuwenhze, M. S.; Sharpless, K. B., Catalytic asymmetric dihydroxylation. Chem. Rev. 1994, 94 (8), 2483-2547; (b) Figueiredo, H.; Silva, B.; Raposo, M. M. M.; Fonseca, A. M.; Neves, I. C.; Quintelas, C.; Tavares, T., Immobilization of Fe(III) complexes of pyridazine derivatives prepared from biosorbents supported on zeolites. Microporous Mesoporous Mater. 2008, 109 (1–3), 163-171; (c) Figueiredo, H.; Silva, B.; Quintelas, C.; Raposo, M. M. M.; Parpot, P.; Fonseca, A. M.; Lewandowska, A. E.; Bañares, M. A.; Neves, I. C.; Tavares, T., Immobilization of chromium complexes in zeolite Y obtained from biosorbents: Synthesis, characterization and catalytic behaviour. Appl. Catal., B: Environ. 2010, 94 (1–2), 1-7.
5. (a) Cheng, Y.; Ma, B.; Wudl, F., Synthesis and optical properties of a series of pyrrolopyridazine derivatives: deep blue organic luminophors for electroluminescent devices. J. Mater. Chem. 1999, 9 (9), 2183-2188; (b) Achelle, S.; Rodríguez-López, J.; Bureš, F.; Robin-le Guen, F., Dipicolylamine styryldiazine derivatives: Synthesis and photophysical studies. Dyes Pigments 2015, 121, 305-311; (c) Cvejn, D.; Achelle, S.; Pytela, O.; Malval, J.-P.; Spangenberg, A.; Cabon, N.; Bureš, F.; Robin-le Guen, F., Tripodal molecules with triphenylamine core, diazine peripheral groups and extended p-conjugated linkers. Dyes Pigments 2016, 124, 101-109.
6. Raposo, M. M. M.; Sampaio, A. M. B. A.; Kirsch, G., A convenient access to thienyl-substituted phthalazines. J. Heterocycl. Chem. 2005, 42 (7), 1245-1251.

Byrsonima crassifolia leaves were extracted via maceration (BrMa), percolation (BrPer), soxhlet (BrSox) and sonication (BrSon). Spectrophotometric estimation of chlorophylls and analysis of cumulative extraction allowed the characterization of the extraction process. Under these experimental conditions, the extraction efficiency for each method was greater than 99%. The best yield was recorded by Soxhlet (7.29±0.21%), the best extraction rate was by sonication (m: 0.032±0.004; r²: 0.96±0.02) and maceration showed less variations in the estimation of chlorophyll a and b. On the other hand, pharmacological evaluation in a rat ileum strips allowed identify that BrMa, BrPer, BrSox and BrSon reduce the spontaneous contractions (E_max: 38.54±2.03, 28.9±1.6, 31.87±1.79, and 29.09±1.27%; EC₅₀: 11.6±2.38; 13.22±2.83; 39.74±2.64 and >50 µg/mL, respectively) of ileum strips in a concentration-dependent manner, however, the effects were significantly lower than papaverine (E_max: 59.32±2.57%; EC₅₀: 7.11±1.0 µg/mL). These results indicated that according to extraction method there are variations in the metabolic content as well as in the pharmacological actions induced by B. crassifolia extracts. Finally, there are a low correlation between extraction temperature (r > 0.87) and spasmolytic activity.

Microwave absorption has attracted a considerable attention in the last decade. Various factors have effect on the microwave attenuation such as permittivity and permeability of absorbers. In this research, these properties were provided by multiwall carbon nanotube (MWCNT) as a conductive polymer and Zn_0.25Co_0.75Fe₂O₄ as a magnetic nanoparticle. MWCNTs were functionalized with carboxylic acid groups through the sonochemical method by the mixture of nitric and sulfuric acid, due to their better dispersion in the medium reaction and enhancing interfacial polarization, and then magnetic nanoparticles were formed base on the functionalized MWCNTs through the solvothermal method by use of ethylene glycol as a solvent. Finally, MWCNT/Zn_0.25Co_0.75Fe₂O₄ nanocomposite was blended in the silicone rubber as a polymeric matrix to investigation of microwave absorption properties. Zn_0.25Co_0.75Fe₂O₄ nanoparticles and MWCNT/Zn_0.25Co_0.75Fe₂O₄ nanocomposite were identified by the diffuse reflection spectroscopy (DRS), Fourier transform infrared (FT-IR), field emission scanning electron microscopy (FE-SEM), and investigation of microwave absorption properties was performed by vector network analyzer (VNA). Results indicated that magnetic nanoparticles and magnetic and dielectric MWCNT/Zn_0.25Co_0.75Fe₂O₄ nanocomposite have been prepared and absorbed more than 47% of microwave at x-band. Moreover, maximum reflection loss of this nanocomposite was 15 dB at 11.96 GHz.

Amino acid based surfactants have been widely used as alternative to classical surfactants due to their interesting physicochemical properties, biological activities, biodegradability and low toxicity. The study of the physicochemical properties of surfactants such as critical micelle concentration (CMC) and Krafft temperature is an important aspect in determining their use in detergents or pharmaceutical compositions. In this study, a series of non-ionic and cationic surfactants with varying chain lengths (C8-C12), namely the O-alkyl esters of methionine and their hydrochloride derivatives respectively were synthesized and characterized by spectral data. In view of systematically studying the effect of the head group and chain length on the physicochemical properties, the critical micelle concentrations of both series were evaluated using conductivity measurements and pyrene fluorescence spectroscopy. The Krafft temperatures of selected synthesized methionine-based surfactants were also evaluated.
The methionine surfactants were synthesized in good to moderate yield (54 – 81%). For both ester and the hydrochloride series, the CMC of the surfactants were found to decrease with chain length, as commonly observed for all surfactants. The non-ionic O-alkyl esters of methionine displayed relatively lower CMC values compared to their ester hydrochloride derivatives for all the chain length studied. The ester hydrochloride derivatives showed an increase in the Krafft temperature with increasing chain length showing that the surfactants with longer chain length has a tendency to micellise at a much higher temperature.

Xanthane hydride (5-Amino-3H-1,2,4-dithiazole-3-thione) reacts with dicyandiamide to afford new 1,3,5-thiadiazine derivative. Xanthane hydride was found to be moderately active antidote
towards herbicide 2,4-D, plant growth regulator and steel corrosion inhibitor.