Labels can be attached to proteins, for example antibodies, which accumulate in specific organs for imaging in animals and human subjects. However, there is a growing realization that imaging events in cells and whole organisms by fluorescence is limited by the accessible probes. 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dyes tend to be strongly UV-absorbing small molecules that emit relatively sharp fluorescence peaks with high quantum yields. They are relatively insensitive to the polarity and pH of their environment and are reasonably stable to physiological conditions. Moreover, small modifications to their structures enable tuning of their fluorescence characteristics. Therefore, these dyes are widely used to label proteins and DNA, among others. Consequently, there is the potential that modifications to the BODIPY framework will lead to probes that can be used more effectively for imaging in living cells and whole organisms, but that it is still largely unrealized.

Having in mind earlier studies, by other groups, and also the research developed recently by our group, we report in this work the synthesis and evaluation of the optical properties of BODIPY derivatives having in mind their potential application as novel fluorescent probes for the detection of a wide range of analytes, such as neutral molecules and ions, as well for bio-imaging in living cells.

Organic molecules comprising strong electron donors and acceptors groups connected by a π-conjugated system (often designated as donor-π-acceptor or “push-pull” chromophores) are of fundamental importance in materials chemistry due to their wide application in modern technology, such as nonlinear optical (NLO) devices, poled polymers, photovoltaic cells, organic light-emitting diodes (OLEDs), semiconductor materials and in optical data storage devices. Several push-pull molecules containing benzothiazole as an (auxiliary) electron-withdrawing group have already been reported, and typically exhibit favorable fluorescence, electrochemical, solvatochromic, photochromic, and NLO properties. We have reported the synthesis and characterization of the UV–vis, solvatochromic, thermal and second-order NLO properties of benzothiazole derivatives containing bithienyl, arylthienyl and thienylpyrrolyl heterocyclic π-spacers in order to evaluate the effect of different π-excessive donor moieties/π-bridges on their optical properties. As an extension of our earlier work and in order to improve the thermal stability and NLO properties of heterocyclic chromophores of the benzothiazole type, we decided to synthesize arylthienyl-benzothiazoles bearing a vinyl spacer between the donor π-excessive heterocycle (thiophene) and the acceptor π-deficient benzothiazole moiety. In this work we report the synthesis and characterization of the optical and thermal properties of a series of vinyl-benzothiazole derivatives as second harmonic generators (SHG) for NLO applications.

Acknowledgements

We are grateful to the Fundação para a Ciência e Tecnologia (FCT) for a post-doctoral grant to R.M.F. Batista (SFRH/BPD/79333/2011), and FEDER (European Fund for Regional Development)-COMPETE-QREN-EU for financial support through the Chemistry Research Centre of the University of Minho (Ref. UID/QUI/00686/2013 and UID/QUI/0686/2016) and the Physics Centers of the Universities of Minho and Porto (Ref. UID/FIS/04650/2013). 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.

In the past few decades, metal-organic frameworks (MOF) have attracted much attention of chemists all over the world, because of their esthetic topological architectures and potential applications in many fields such as gas storage and separation, catalysis, magnetism, optics, ion conductivity, luminescence and drug delivery. The structures of these crystalline materials consist of metal ion, organic ligand and solvents. Aromatic polycarboxylate ligands as a kind of multidentate O-donor ligands, have been extensively employed in the preparation of MOFs.

In this work, the title MOF was synthesized by mixing calcium salt and benzene-1,2,4,5-tetracarboxylic acid in a mixture of water and alcohol; which was characterized by X-ray diffraction, FT-IR and photoluminescence spectroscopy methods.

Polyfunctionalized benzene derivatives 1 and 2 consist of important structural units in organic synthesis presente in certain molecules that existe in many and varied applications (pharmaceutical, biological, cosmetic ...). In this work, we have synthesized polyfunctionalized benzene derivatives 1, 2 from current and inexpensive reagents: β-ketoesters salicylic aldehyde and alkyl halides. The results obtained demonstrate the interesting strategy which has been chosen for the synthesis of this type of polyfunctionalized benzene derivatives 1.2. The compounds obtained spectroscopic analysis made it possible to identify the structure of the different products isolated in the form of a single stereoisomer designed as E-configuration. In fact, we have obtained the following seven condensation products:

1-(E)-methyl 2-(3-(2-(allyloxy)phenyl)acryloyl)pent-4-enoate

2-(E)-methyl 5-(2-(allyloxy)phenyl)-3-oxo-2-(prop-2-ynyl)pent-4-enoate

3-(E)-methyl 2-(3-(2-(but-3-enyloxy)phenyl)acryloyl)pent-4-enoate

4-(E)-methyl 5-(2-(but-3-enyloxy)phenyl)-3-oxo-2-(prop-2-ynyl)pent-4-enoate

5-(E)-methyl 2-(3-(2-(pent-4-enyloxy)phenyl)acryloyl)pent-4-enoate

6-(E)-methyl 3-oxo-5-(2-(pent-4-enyloxy)phenyl)-2-(prop-2-ynyl)pent-4-enoate

7-(E)-methyl 2-(3-(2-(prop-2-ynyloxy)phenyl)acryloyl)pent-4-enoate

The chemistry of cyclometalated compounds has attracted much research interest in past years. They are known for their ample applications in numerous fields: organic synthesis, photochemistry, catalysis, and as potential biologically active materials. Numerous Palladacycles bearing Ph₂PCH₂PPh₂-P,P, (dppm) were described before showing different ways of coordination.

We now report Palladacycles of the type [Pd₂(Ph₂PCH₂PPh₂−P,P)₂(C,N:C,N)] can undergo a spontaneous slow chelate−to−bridging diphosphine coordination shift in solution when (C,N:C,N) is derived from −4,4´−sulfonyldianiline or −4,4´−oxydianiline and 2,3,4-trimethoxybenzylidene. Following this strategy a synthetic procedure was devised that culminates in isolation of the first crystallographically characterized tetranuclear palladium structures.

Xanthones, a type of compounds widely found in many natural products from plants, fungi and lichens, are considered privileged structures. Frequently, xanthones occur in Nature as dimers, which often exhibit singular and potent biological effects. Although diverse methods for the synthesis of monomeric xanthones are known, dimeric xanthones remain synthetically challenging targets. Reported syntheses of dimeric xanthones are very scarce, and invariably involve a large number of synthetic steps.

We have recently developed a multicomponent synthesis of xanthones starting from 3-carbonylchromones, isocyanides and dienophiles.¹ Here we report a similar one pot tandem procedure, involving a [4+1]−[4+2] cycloaddition, that readily affords dimeric xanthones and dihydroxanthones structurally similar to bioactive ergochromes.²

References:

(1) Bornadiego, A.; Diaz, J.; Marcos, C. F. Adv Synth Catal 2014, 356, 718.

(2) Bornadiego, A.; Diaz, J.; Marcos, C. F. J Org Chem 2015, 80, 6165.

Nitro compounds are compounds of great versatility in organic synthesis due to their easy availability and transformation into a wide variety of functionalities.[1] As a part of our continued interest in nitro compounds, we few years ago reported the transformation of 3-(4,5-dimethoxy-2-vinylphenyl)-2-methyl-5-nitroisoquinolin-1(2H)-one (1) into 2-(6,7-dimethoxy-1-oxoisoquinolin-2(1H)-yl)-N-methylbenzamide (4), via 3-(4,5-dimethoxy-2-vinyl- phenyl)-2-methyl-5-nitroisoquinolin-1(2H)-one (2) and 3-(2-(2,2-dimethoxyethyl)-4,5-dimethoxy-phenyl)-2-methyl-5-nitroisoquinolin-1(2H)-one (3).[2]

A mechanistic proposal for the novel, striking rearrangement of compound 3 to compound 4 will be discussed.

Selenium is an essential trace element. In Nature, its main biological function is associated with the incorporation in the form of selenocysteine into certain proteins having redox motifs, such as Glutathione Peroxidase (GPx), among others. Different selenium containing compounds resulted to be bio-inspired catalysts, good antioxidant agents and good GPx-mimics. On the other hand, chitosan the chiral polysaccharide obtained by alkaline deacetylation of chitin has been applied in many fields, due to its biocompatible and biodegradable properties as well as its relative ease to manage compared to its chemical N-acetylated precursor. The control of their chemical and physical properties allows chitosan derivatives to be used for different biomedical and industrial applications. Degree of deacetylation (DD) and polymer chain length (molecular weight, Mw) can be considered the most important features to determine the physico-chemical properties of these systems and consequently decisive factors to give desired results in formulations and applications.

We report here, the synthesis of new selenoureidyl chitosan derivatives with tunable physicochemical properties by reaction of the biopolymer with a series of diversely substituted aryl isoselenocyanates. All new compounds have been characterized by NMR techniques both in solution and in solid state. Finally, in order to study the applicability of the new chitosan-derived selenoureas, antioxidant capacity and GPx-mimics ability have been investigated.

The authors thank the Junta de Andalucía (2011/FQM-142, and Project P09-AGR-4597); Spanish Ministerio de Economía, Industria y Competitividad (MINECO), Spain (CTQ2016-78703-P); A. J. Galera-Carrillo also thanks Universidad de Sevilla (PEJUS-2, 2017-2-EJ-070) for funding support. The authors also thank the CITIUS, Universidad de Sevilla, for the facilities.

Four new a-b-unsaturated alkyl-ester chiral amines were synthesized in excellent yields (84–95%) via peptide couplings from their corresponding a-b-unsaturated alkyl-ester anilines and N-Boc protected chiral aminoacids. To our delight, these polyfunctionalized compounds are being used as starting reagents in Ugi-type three-component reactions (Ugi-3CR), together with alkyl- and aryl-aldehydes, and a couple of chain-ring tautomerizable aminoacid-containing isocyanides to synthesize novel oxazole-based macrocycle precursors. Thus, the aim of this communication is to show our most recent results of the synthesis and use of new and complex chiral amines to assemble macrocyclic polypeptides with potential application in medicinal chemistry, such as the post-surgical antibiotic Vancomycin.

The uB3LYP/6-311g++(d,p) method in the gas phase was used to simulate the reaction of ethylene with ortho, meta, para: methylnitrobenzene, chloronitrobenzene, (CCl₃)PhNO₂, (CF₃)PhNO₂ in the T₁ state, as well as determined the influence of the position of donor and acceptor substituents in the benzene ring on the activation energy of the reaction under study. It is established that during the reaction ethylene oxide and nitroso compound are formed.