Spiranic O-BODIPYs bearing a phenol-based bi(polyarene) unit tethered to the boron center through oxygen atoms constitute an interesting family of BINOL-BODIPY dyads useful for the development of photonic applications due to their synthetic accessibility and tunable photonic properties. We found previously that the electron-donor capability of the involved BINOL moiety switched on a non-emissive intramolecular charge transfer (ICT) state, which restricted the fluorescence efficiency of the dyad. We demonstrated that the influence of this non-radiative deactivation channel can be efficiently modulated by the substitution pattern, either at the dipyrrin core or at the polyarene moiety, being possible to diminish or even virtually cancel the ICT probability, and hence achieve bright fluorescence upon dual excitation at far-away spectral regions.¹

Additionally, we demonstrated that this simple structural motif exhibits chiroptical properties (circular dichroism, CD, and circularly polarized luminescence, CPL), as a consequence of the chiral perturbation exerted by the BINOL-based unit over the inherently achiral BODIPY chromophore.²

Based on these previous results, we found interesting to carry out a comprehensive study on the influence of the structure of both the BODIPY chromophore and the BINOL moiety over the chiroptical properties of this family of O-BODIPYs, directed to the improvement of said properties for their use in photonic applications. This communication reports the most important preliminary results obtained from this study, directed to the design of improved BODIPYs for Chiroptics.

[1] Gartzia-Rivero, L.; Sánchez-Carnerero, E. M.; Jiménez, J.; Bañuelos, J.; Moreno, F.; Maroto, B. L.; López-Arbeloa, I.; de la Moya, S. Modulation of ICT probability in bi(polyarene)-based O-BODIPYs: towards the development of low-cost bright arene-BODIPY dyads. Dalton Trans. 2017, 46, 11830.

[2] Sánchez-Carnerero, E. M.; Moreno, F.; Maroto, B. L.; Agarrabeitia, A. R.; Ortiz, M. J.; Vo, B. G.; Muller, G.; de la Moya, S. Circularly Polarized Luminescence by Visible-Light Absorption in a Chiral O-BODIPY Dye: Unprecedented Design of CPL Organic Molecules from Achiral Chromophores. J. Am. Chem. Soc. 2014, 136, 3346.

N-BODIPYs (diaminoborondipyrromethenes) have been recently described by us for the first time as a new family of BODIPY dyes with huge technological potential. This new dyes retain the effective photophysical behavior exhibited by other boron-substituted BODIPYs, such as O-BODIPYs. However, key bonding features of nitrogen compared to those of oxygen (enhanced bond valence and different bond directionality) open up new possibilities for functionalizing BODIPYs, for example the existence of more pendant moieties near the chromophore (from two in O-BODIPYs, up to four in N-BODIPYs). This fact increases the synthetic versatility of the new dyes and, therefore, increases the possibilities for controlling their photophysics.¹

On the other hand, we have also designed a simple new structural motif to achieve circularly polarized luminescence (CPL) from inherently achiral monochromophore systems. This design is based on a spiranic BINOL-derived O-BODIPY dye and provides CPL levels (|g_lum|) in solution falling into the usual range (10⁻⁵ to 10⁻²) of that obtained from other simple organic molecules (SOM).^2,3

With the aim of expanding the up-to-now limited number of structures for CPL-SOMs, we have combined together the two new findings (N-BODIPY and CPL-active monochromophoric spiranic BODIPY) to synthesize a series of chiral spiranic N-BODIPYs. The study of the circular dichroism (CD) of these BODIPYs will provide a first insight into the potential of these new dyes in Chiroptics, including CPL. This communication reports the most important results concerning the conducted study.

[1] Ray, C.; Díaz-Casado, L.; Avellanal-Zaballa, E.; Bañuelos, J.; Cerdán, L.; García-Moreno, I.; Moreno, F.; Maroto, B. L.; López-Arbeloa, Í.; de la Moya, S., N-BODIPYs Come into Play: Smart Dyes for Photonic Materials. Chem. Eur. J. 2017, 23 (39), 9383-9390.

[2] Sánchez-Carnerero, E. M.; Moreno, F.; Maroto, B. L.; Agarrabeitia, A. R.; Ortiz, M. J.; Vo, B. G.; Muller, G.; de la Moya, S., Circularly Polarized Luminescence by Visible-Light Absorption in a Chiral O-BODIPY Dye: Unprecedented Design of CPL Organic Molecules from Achiral Chromophores. J. Am. Chem. Soc. 2014, 136 (9), 3346-3349.

[3] Sánchez-Carnerero, E. M.; Agarrabeitia, A. R.; Moreno, F.; Maroto, B. L.; Muller, G.; Ortiz, M. J.; de la Moya, S., Circularly Polarized Luminescence from Simple Organic Molecules. Chem. Eur. J. 2015, 21 (39), 13488-13500.

Phytoestrogens are plant compounds which have generated considerable interests. A litany of health benefits including a lowered risk of osteoporosis, heart disease, breast cancer, and menopausal symptoms, are frequently attributed to phytoestrogens but without the knowledge of their side effects. Consequently, the question of whether or not phytoestrogens are beneficial or harmful to human health remains unresolved. Here, we investigate the effects of lipid extracts from the Solanaceae Nicotiana glauca on skeletal muscle cells, in relation to apoptosis. Previously, we evidenced the presence of molecules functional and structurally analogous to 17β-estradiol in extracts of Solanaceaes.  We performed extraction and phytochemical screening as per the standard methods of Wagner (1984), using Dragendroff’s, Bornträger´s and Libermann-Burchard’s test.  The effects of lipids extracts from N. glauca in C2C12 cells were analyzed by Mitotracker DAPI, TUNEL and immunofluorescence staining and Western blotting. Caspase activity was analyzed with a commercial kit.

Opposite to the effects of 17β-estradiol, the crude extract from N. glauca and its sub-extracts obtained by partition, induced apoptosis in C2C12 cells. This apoptotic action involved caspase 3/7 activation. Also, we evidenced that the extracts from N. glauca trigger a rapid defense response in skeletal muscle through Akt and HSP27-phosphorylation. The data reported here, on the effects of lipid extracts from N. glauca on myoblasts suggest that the traditional use of this medicinal plant could affect the skeletal muscle homeostasis.

We have recently reported on the control of Vilsmeier-Haack processes in meso-methylBODIPYs with activated DMF as the electrophilic reagent.¹ Such a control allows the selective generation of beta-formylBODIPYs, BODIPY meso-enamines or BODIPY meso-iminium/enamine salts, by selecting properly the substitution pattern in the starting BODIPY, the hard (or soft) nature of the activated-DMF reagent, as well as the reaction conditions.¹ It was also shown that meso-enamination deeply alters the photophysical properties of the BODIPY chromophore, quenching efficiently the fluorescence by the activation of non-radiative de-excitation channels, including intramolecular charge transfer (ICT), which in turn enables singlet-oxygen generation.¹

This result, easy generation of a family of BODIPYs with potentiality to act as singlet-oxygen photosensitizers for photodynamic therapy (PDT)² without involving heavy atoms or complex polyBODIPY designs, prompted us to detailed explore the scope of such a possibility. This presentation shows the results obtained from such an exploration, by reporting the most interesting results concerning singlet-oxygen generation in a selected family of BODIPY meso-enamines.

[1] Palao, E.; Montalvillo-Jiménez, L.; Esnal, I.; Prieto-Montero, R.; Agarrabeitia, A. R.; García-Moreno, I.; Bañuelos, J.; López-Arbeloa, I.; de la Moya, S.; Ortiz, M. J., Controlling Vilsmeier-Haack processes in meso-methylBODIPYs: A new way to modulate finely photophysical properties in boron dipyrromethanes. Dyes Pigments. 2017, 141, 286.

[2] a) Kamkaew, A.; Lim, S. H.; Lee, H. B.; Kiew, L. V.; Chung, L. Y.; Burgess, K., BODIPY dyes in photodynamic therapy. Chem. Soc. Rev. 2013, 42, 77. b) Awuah, S. G.; You Y., Boron dipyrromethane (BODIPY)-based photosensitizers for photodynamic therapy. RSC Adv. 2012, 2, 11169.

We have investigated mechanism off the hydrogen atom abstraction from H2S by triplet CrO3, MoO3 and WO3 by quantum chemical ub3lyp/lanl2dz method. Activation energy of the CrO3 + H2S, MoO3+H2S, WO3+H2S reactions were calculated as: 2.45 kcal/mol, 2.41 kcal/mol, 2.16 kcal/mol. These values were greater than in the corresponding ones in the singlet state.  Beside we have investigated the spin density distribution in the transition states all them calculated. Allocated spin density has said about spin density transition from one oxygen centre to sulfur atom. Transition have been uncompleted (because value sulfur’s spin density was equal 0.429, at the same time spin density on oxygen atom was of 0.631 in the case of the CrO3 + H2S reaction). Transition in the transition state has not led to great change in difference between HOMO and LUMO for all system studied. The mechanism of the reaction have been proposed.

Abstract

Macrocyclic compounds with pendant-arms are designed with two principal aims: modification of the coordinating properties of the parent ligand, and introduction of the ancillary groups in order to provide a specific application in a particular area of scientific research such as bioinorganic chemistry [1], anionic receptors [2], contrast agents in medicine [3], and so forth.The synthesis of a new trans-substituted organic ligand with methylpyridine groups stemming from a precursor with secondary amines, allows to optimize its ability to coordinate to transition metals and lanthanide ions [4].

References

[1] D. E. Fenton, “Biocoordination Chemistry”, Oxford University Press. 1993.

[2] J. K. Lee, J. Na, T. H. Kim, Y.-S. Kim, H. Won, T. S. Lee, “Synthesis of polyhydroxybenzoxazole-based colorimetric chemosensor for anionic species”, Materials Science and Engineering, 2004, 24, 261.

[3] M. Botta, Eur. J. Inorg. Chem., 2000, 399.

[4] K. P. Wainwright, Adv. Inorg. Chem., 2001, 52, 293.

Acknowledgements

This work was made possible thanks to the financial support received from the Xunta de Galicia (Galicia, Spain) under the Grupos de Referencia Competitiva Programme (Project GRC2015/009). F.L.−M. thanks the Spanish Ministry of Education (grant FPU13/05014).

Abstract

In the past, magnetic resonance imaging (RMI) has become an ever popular diagnosis method in medicine. The use of increased relaxation rates of protons in water has significantly improved the quality of the image. An example of this type of contrast agents are the compounds formed by Gd(III) with DOTA or DPTA ligands, which contain carboxyl groups, that can be prepared from ligands with dioxolane groups. These agents must have a high effective magnetic momento and for this reason Gd(III) is chosen to coordinate these ligands [1], [2].

 From macrocycles with secondary amino groups in trans positions, tetra- or di- substituted compounds were obtained by direct reaction with dioxolane groups [3], which can be separated by recrystallization for further study as lanthanide ion receptors.

References

[1] Q. Zheng, H. Dai, M. E. Merritt, C. Malloy, C. Y. Pan, W. Li, J. Am. Chem. Soc., 2005, 127, 16178.

[2]  M. K. Moi, C. F. Meares, S. J. De Nardo, J. Am. Chem. Soc., 1988, 110(18), 6266.

[3] C. Núñez, R. Bastida, A. Macías, A. Aldrey, L. Valencia, Polyhedron, 2010, 29(1), 126.

Acknowledgements

This work was made possible thanks to the financial support received from the Xunta de Galica (Galicia, Spain) under the Grupos de Referencia Competitiva Programme (Project GRC2015/009). F.L.−M. thanks the Spanish Ministry of Education (grant FPU13/05014).

Benz[X]azole derivatives are interesting compounds due to their diverse biological activities¹ and interesting optical properties.²  The benzothiazole, benzimidazole, and benzoxazole heterocycles are heteroaromatic electron deficient moieties that act as both acceptor groups and pi-conjugated spacers with auxiliary electron withdrawing ability.^2,3 Moreover, benzimidazole derivatives offers the possibility of substitution on the nitrogen atom for further tuning of their optical and electronic properties.

Recently we have reported the synthesis and evaluation of the electronic, thermal and optical properties of a large number of series of benz[X]azole derivatives functionalized with different π-spacers having in mind their application as optical chemosensors, nonlinear optical and photochromic materials, and emissive organic components for OLEDs.²

In continuation of the work developed by our research group, we report in this communication the synthesis, the characterization and the evaluation of the optical properties of four novel 1-(4-thiophene-2-yl)phenyl)-1H-pyrrole derivatives functionalized with different benz[X]azole moieties (benzothiazole, benzimidazole, and benzoxazole). The results showed that the optical properties could be readily tuned by changing the electronic nature of the azole ring, or even by the introduction of a strong acceptor group.

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 within the framework of the National Program for Scientific Re-equipment, contract REDE/1517/RMN/2005 with funds from POCI 2010 (FEDER) and FCT.

 References

1. (a) Boiani, M.; Gonzalez, M., Imidazole and benzimidazole derivatives as chemotherapeutic agents. Mini-Rev. Med. Chem. 2005, 5 (4), 409-424; (b) Keri, R. S.; Patil, M. R.; Patil, S. A.; Budagumpi, S., A comprehensive review in current developments of benzothiazole-based molecules in medicinal chemistry. Eur. J. Med. Chem. 2015, 89 (Supplement C), 207-251.
2. (a) Costa, S. P. G.; Batista, R. M. F.; Cardoso, P.; Belsley, M.; Raposo, M. M. M., 2-Arylthienyl-substituted 1,3-benzothiazoles as new nonlinear optical chromophores. Eur. J. Org. Chem. 2006, 3938-3946; (b) Batista, R. M. F.; Costa, S. P. G.; Belsley, M.; Raposo, M. M. M., Synthesis and second-order nonlinear optical properties of new chromophores containing benzimidazole, thiophene, and pyrrole heterocycles. Tetrahedron 2007, 63 (39), 9842-9849; (c) Batista, R. M. F.; Costa, S. P. G.; Malheiro, E. L.; Belsley, M.; Raposo, M. M. M., Synthesis and characterization of new thienylpyrrolyl-benzothiazoles as efficient and thermally stable nonlinear optical chromophores. Tetrahedron 2007, 63 (20), 4258-4265; (d) Batista, R. M. F.; Ferreira, R. C. M.; Raposo, M. M. M.; Costa, S. P. G., Novel optical chemosensors for anions and cations based on an amino acid core functionalized with benzimidazoles. Tetrahedron 2012, 68 (36), 7322-7330; (e) Pina, J.; Seixas de Melo J. S.; Batista, R. M. F.; Costa, S. P. G.; Raposo, M. M. M. Triphenylamine-benzimidazole derivatives: synthesis, excited-state characterization, and DFT studies. J. Org. Chem.2013, 78 (22), 11389-11395; e) Castro, M. C. R.; Belsley, M.; Raposo, M. M. M., Push–pull second harmonic generation chromophores bearing pyrrole and thiazole heterocycles functionalized with several acceptor moieties: syntheses and characterization. Dyes Pigments 2016, 128, 89-95; f) Garcia-Amorós, J.; Castro, M. C. R.; Coelho, P.; Raposo, M. M. M.; Velasco, D. Fastest non-ionic azo dyes and transfer of their thermal isomerization kinetics into liquid-crystalline materials. Chem. Commun. 2016, 52 (29), 5132-5135.
3. Revuelta, J.; Machetti, F.; Cicchi, S., Five-membered heterocycles: 1,3-azoles. In Modern Heterocyclic Chemistry, Wiley-VCH Verlag GmbH & Co. KGaA: 2011; pp 809-923.

The ring closing enyne metathesis reactions have been applied to systems derived from homopropargylic alcohol backbones are described. The key intermediates 2-benzofuranyl and 2-benzothiophenyl homopropargylic alcohols were synthesized from their corresponding carboxyaldehyde derivatives and resolved to give the corresponding enantiopure acetates and the alcohols with high ee values through enzymatic resolution. Then, enantiomerically enriched enyne skeletons derived from homopropargylic alcohols were subjected to the ring closing metathesis reaction via first generation Grubbs' catalysts and corresponding chiral heteroaryl-substituted dihydropyran derivatives were obtained with good yields.

The effect of substituent on the aromaticity of phosphazene has been investigated theoretically by the application of density functional theory at the level of B3LYP/6-31+G(d,p) method. Phosphazene is isoelectronic with benzene, pyridine or other 6π systems. However, appearance of three phosphorus together with three electronegative nitrogens leads to a non-aromatic ring. Therefore, substituents may have potential to enhance the aromaticity of the parent structure. Both electron donating and electron withdrawing substituents have been replaced with the hydrogens on phosphorus. Nucleus-independent chemical shift (NICS) data have been considered to determine the aromaticity of the systems.