Organic salts are the focus of much recent attention, in part due to their stability and the ease of tailoring for specific physical properties. In particular, styryl-pyridinium and benzothiazolium salts have been widely applied in diverse areas such as NLO-phores, frequency-upconversion, optical power limiting, fluorescent probes, laser scanning fluorescence microscopy, molecular switches, etc.¹ The recognition and detection of ionic species has aroused great interest due to their important roles in many biological and environmental processes. Several sensor systems have been developed but most present some limitations in terms of sensitivity, selectivity, and simplicity. Colorimetric chemosensors are molecules that allow naked-eye detection of ionic species without resource to any instrumentation, offering qualitative and quantitative information. These chemical sensors are considered as one of the most effective analytical methods for environmental monitoring, particularly in the detection of metal ions whose presence in the environment has serious consequences. Additionally, chemosensors soluble in aqueous media are very interesting, because of the importance in sensing species in biological processes, disease states and environmental pollution.²

In this communication, we report the synthesis of two benzothiazolium salts 3a-b, substituted at position 2 with a triphenylamino donor group and an aryl spacer with different electronic character, in order to evaluate their photophysical properties and chemosensory ability. Organic salts 3 were synthesized through Knoevenagel reaction between the precursor aldehydes 2 and 1-methylbenzothiazolium salt 1 in moderate to good yields. The new derivatives were characterized by the usual techniques and a detailed photophysical study was undertaken. The evaluation of the compounds as colorimetric chemosensors 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 (PEst-C/QUI/UI0686/2013 (FCOMP-01-0124-FEDER-037302)), 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) Zajac M.; Hrobarik P.; Magdolen P.; Zahradník P. Tetrahedron 2008, 64, 10605. b) Brown A. S.; Bernal L.-M.; Micotto T. L.; Smith, E. L.; Wilson J. N. Org. Biomol. Chem. 2011, 9, 2142. c) Xu, J.-F.; Chen, H.-H.; Chen, Y.-Z.; Li, Z.-J.; Wu, L.-Z.; Tung, C.-H.; Yang, Q.-Z. Sens Actuators B, 2012, 168, 14-19. d) Chao, J.; Li, Z.; Zhang, Y.; Huo, F.; Yin, C.; Liu, Y.; Li, Y.; Wang, J. J. Mater. Chem. B, 2016, 4, 3703-3712. e) Bures, F.; Cvejn, D.; Melánová, K.; Benes, L.; Svoboda, J.; Zima, V.; Pytela, O.; Mikysek, T.; Ruzickova, Z.; Kityk, I. V., Wojciechowski, A.; AlZayed, N. J. Mater. Chem. C, 2016, 4, 468-478. f) Coelho, P. J.; Castro, M. C. R.; Raposo, M. M. M. Dyes Pigments, 2015, 117, 163-169.
2. a) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. J. Photochem. Photobiol. A, 2013, 259, 33-40. b) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. Sens Actuators B, 2014, 191, 791-799. c) Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. Dyes Pigments, 2014, 102, 293-300. d) Marín-Hernández C.; Santos-Figueiroa, L. E.; Moragues, M. E.; Raposo, M. M. M.; Batista, R. M. F.; Costa, S. P. G.; Pardo, T.; Martínez-Mánez, R.; Sancénon, F. J. Org. Chem., 2014, 79, 10752-10761.

The one-pot synthesis of novel 1,4-disubstituted 1,2,3-triazoles from isoquinoline-substituted homopropargyl alcohol backbone is described (42%-88% yields) (Scheme 1). A ring closing metathesis reaction and an intramolecular Pauson-Khand reaction of enyne system derived from a homopropargyl alcohol backbone to afford the corresponding isoquinoline-substituted dihydropyran and cyclopentenone-pyran, respectively, are also described (54% and 78% yields) (Scheme 2). Information about the structural, electronic, and physico-chemical properties of the novel hybrid compounds, obtained by density functional theory application, is also reported.

The stereoselective synthesis of a variety of 3-substituted isobenzofuranones has been developed through a new and flexible route. When combined with a catalytic amount of benzoic acid, quinidine thiocarbamate bifunctional catalysts have demonstrated their efficiency for the enantioselective bromolactonization reaction of styrene-type carboxylic acids bearing an alkoxycarbonyl electron withdrawing group on the carbon-carbon double bond.

Benzimidazole derivatives are among the most significant classes of bioactive molecules in drugs and pharmaceuticals. The construction of these heterocycles has received an increasing attention to synthetic organic chemists and biologists [1]. During recent decades, numerous heterogeneous catalysts have been proposed and employed for constructing the benzimidazole. On the other hand, graphene-based polymer nanocomposites have attracted strong interest due to their novel properties or enhanced performance [2]. In this work, we reported the synthesis of benzimidazole derivatives via the condensation of benzene-1, 2-diamines with benzaldehyde derivatives catalyzed by Graphene-based polymer nanocomposites under mild conditions in moderate to good yields.

References

 [1] Zhan-Hui Zhang, Liang Yin, Yong-Mei Wang, Catalysis Communications, 8, 1126–1131, (2007).

 [2] Li Wang, Xingping Lu, Shengbin Lei, Yonghai Song, Journal of Materials Chemistry A, 2, 4491-4509, (2014).

An efficient protocol was developed for the four component and one-pot synthesis of functionalized 1, 4-dihydropyridines by thiamine (VB1) as biocatalyst via the reaction of malononitrile, substituted aldehydes, dimethylacetylenedicarboxylate and substituted aniline in ethanol at room temperature. Reactions were completed in 80 min. Availability and non-toxicity are the advantages of this green catalyst. Also, easy work-up, no chromatographic purifications and high yields in short reaction time are the advantages of this procedure.

References

[1] Mandhane, P. G., Joshi, R. S., Nagargoje, D. R., Gill, C. H., Chinese Chemical Letters, 22, 563–566, (2011).
[2] Sharma, P., Gupta, M., Journal of Chemical Sciences, 128, 61–65, (2016).

Catalyst has a noteworthy role in chemical processes in both industrial and scientific fields. Use of catalyst can helps to serve less energy, time and money. As a result, chemical process became more eco-friendly and economical. Nanocatalysts are an important branch in this issue. Multicomponent reactions (MCRs) are one of the most effective strategies in the field of green chemistry; witch is the utilization of a set of principles that reduces or eliminates the use or generation of hazardous substances in the design, manufacture, and application of chemical products. Therefore, by application of nanocatalysts in MCRs, chemical synthesis can approach aims of green and sustainable chemistry. As it is mentioned nanocatalyst, are important field and have many advantages in recent years. Magnetic nanocatalysts are a subdivision of catalyst and beneficial strategy in green chemistry. Biocatalysts are another one either. Meet of these two branches results a new, efficient and green nanocatalyst. Chitosan is a biopolymer and it is used in many organic syntheses as catalyst, supporting this with a magnetic nanocatalystmodified this biocatalyst and enhance its properties, also leads to another efficient and green catalyst.

The purpose of this work is the design, synthesis and characterization of thiosemicarbazone ligands bearing a phenyl boronic acid functionality. The main interest is the synthesis of organopalladium compounds with the boronic acid included within the corresponding molecule. These could lead to further modification of the properties of the organometallic species applicable to the Suzuki-Miyaura reaction.

The ligands were prepared by reaction of acetylphenylboronic acid with several thiosemicarbazides. The compounds were characterized by IR, ¹H and ³¹P NMR spectroscopy.

References:

Adrio, L.A., PhD Dissertation, University of Santiago de Compostela, 2006.

Bermúdez, B., PhD Dissertation, University of Santiago de Compostela, 2014.

Acknowledgments 

We wish to thank the financial support received from the Xunta de Galicia (Galicia, Spain) under the Grupos de Referencia Competitiva Programme Projects GRC2015/009.

Thiosemicarbazones are well known compounds that show antitumoral and antibacterial proprieties[1] ; while crown ether moiety acts as ion sensor to entrap cations size-selectively from the environment, implied in the production of sensors, membrane ion transport or potential anti-cancerous species, among others[2]. The combination of both functions into the same molecule should increase their unique applications.

Herein we report on the synthesis of a molecule that combines both functions. The main aspect is that the study has being performed beginning with the design of the compound using DFT calculations, with the package of programs g09[3], after which follows the final synthesis and characterization using ¹H NMR, IR and crystallographic analysis.

Acknowledgments

We wish to thank the financial support received from the Xunta de Galica (Galicia, Spain) under the Grupos de Referencia Competitiva Programme Projects GRC2015/009. F.Lucio thanks the Spanish Ministry of Education (grant FPU13/05014).

References

[1] (a) A. I. Matesanz, J. M. Pérez, P. Navarro, J. M. Moreno, E. Colacio, P. Souza, J. Inorg. Biochem. 1999, 76. (b) G. Domagk, Quimioteraia de la tuberculosis por las tiosemicarbazonas. Científico Médica, 1951. (c) M. T. Cocco, C. Congiu, V. Onnis, M. L. Pellerano , A. De Logu Bioorganic and Medicinal Chemistry, 2002, 10 501.

[2] (2) (a) C Preihs, D. Magda, J. Sessler J. Porphyrins and Phthalocyanines, 2011, 15, 539. (b) Z. Sun, M. Barboiu, Y-M Legrand, E. Petit, A. Rotaru, Angew. Chem. Int. Ed. 2015, 54, 14473

[3]  M. J. Frisch et al.  Gaussian 09, Revision D.01; Gaussian, Inc., Wallingford CT, 2013.

We propose the concept of the spherical or «ball-shaped») compounds. In this communication we are considered NMR ¹H spectra of 53 «spherical pentanes» - saturated hydrocarbons with a maximum length of the chain of five carbon atoms. Depending on the alkane sphericity these include substances from simplest n-pentane to most complicated tetra(tert-butyl)methane. We introduce the conception of the spherical alkane structure, which includes: a) a central carbon atom of the whole molecule (С³), b) two, three or four carboncontaining branches attached to it. These include monocarbonic methyl (Me) and dicarbonic (longest chain) Et, Prⁱ, Bu^t- fragments. Besides of carboncontaining branches one or two branches may be the hydrogen atoms.

The central atom (С³) is surrounded by three layers, called: a) inner - α-layer, b) intermediate - β-layer, and c) the outer - γ-layer, which is often referred to - ω-layer. The inner and intermediate layers may contain both carbon and hydrogen atoms, but the outer layer contain only hydrogen atoms. We consider several types of alkanes sphericity: «quazi-spherical», «minimally-spherical», and «maximally-spherical», as well as linear (n-pentane) and «quazi-linear».

We consider the values of proton chemical shifts in all 53 investigated spherical alkanes depending on the location of the studied hydrogen atoms in a certain layer.
It has been shown that the number of hydrogen atoms in the outer ω-layer (denoted by the symbol H_ω) and the uniformity of their distribution in the volume of this outer layer (which depends on the type of alkane sphericity) have a significant influence on the studied values of proton chemical shifts in spherical alkanes.

It has been shown that when parameter H_ω = 12 (or 15) we observe the maximal upfield signals shift of all studied protons, except the methyne hydrogens of isopropyl group. Then, with the growth of H_ω parameter we observe an increase of the chemical shifts (downfield shift). It is shown that when the magnitude H_ω is equal to 12 (or 15) we observe for the methyl groups of ethyl fragments in the maximally-spherical compounds the highest upfield shift relative to the accepted standard (the δ^Н_СН3 value of terminal methyl groups of linear long chain alkanes). The same also applies to methylene groups of ethyl fragments.

To explain the observed results, we propose the hypothesis, which is associated with the assumption of interaction to each other of three (or especially four) carboncontaining branches, radiating from the central carbon atom С³ in spherical molecules. This interaction, in our opinion, is similar to the interaction (which we propose earlier) of two (in CH₂XY) or three (in CHXYZ) heteroatoms in the case of «anomeric effect» in compounds with gem-location of heteroatoms X, Y, Z. Namely this interaction, in our opinion, causes the observable upfield shift of the methylene or methyne proton’s signals.

The investigation in ionic liquids (Lis) is in continuous growth, nevertheless many of their results are being reviewed. Our interest is to analyze the behavior of Lis alkylammonium derivatives in cycloaddition reactions analyzing their participation as catalyst and potential nucleophilic generated in situ.