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Encapsulation is one of the technologies applied for the formulation of biological control agents. The function of the encapsulating matrix is to protect the biological material from environmental factors, while dehydration allows for its viability to be prolonged. An advantage of dehydrated encapsulation formulations is that they can be stored for long periods. However, vegetative cells require low-stress dehydration processes to prevent their loss of viability. Herein we describe the fabrication of a dehydrated encapsulate of the Streptomyces CDBB1232 mycelium using sodium alginate with a high concentration of mannuronic acid; sodium alginate was added with YGM medium for mycelium protection purposes. The encapsulation was carried out by extrusion, and its dehydration was carried out in a rotating drum fed with air at room temperature (2–10 L min−1). The drying of the capsules under air flows higher than 4 L min−1 led to viability loss of the mycelium. The viability loss can be decreased up to 13% by covering the alginate capsules with gum arabic. Compared to conventional dehydration processes, air moisture removal can be lengthy, but it is a low-cost method with the potential to be scaled.

Encapsulation is one of the technologies applied for the formulation of biological control agents. The function of the encapsulating matrix is to protect the biological material from environmental factors, while dehydration allows for its viability to be prolonged. An advantage of dehydrated encapsulation formulations is that they can be stored for long periods. However, vegetative cells require low-stress dehydration processes to prevent their loss of viability. Herein we describe the fabrication of a dehydrated encapsulate of the

International audience; One monometallic and three bimetallic ruthenium nitrosyl (RuNO) complexes are presented and fully characterized in reference to a parent monometallic complex of formula [FTRu(bpy)(NO)]3+, where FT is a fluorenyl-substituted terpyridine ligand, and bpy the 2,2’-bipyridine. These new complexes are built with the new ligands FFT, TFT, TFFT, and TF-CC-TF (where an alkyne C≡C group is inserted between two fluorenes). The crystal structures of the bis-RuNO2 and bis-RuNO complexes built from the TFT ligand are presented. The evolution of the spectroscopic features (intensities and energies) along the series, at one-photon absorption (OPA) correlates well with the TD-DFT computations. A spectacular effect is observed at two-photon absorption (TPA) with a large enhancement of the molecular cross-section (σTPA), in the bimetallic species. In the best case, σTPA is equal to 1523±98 GM at 700 nm, in the therapeutic window of transparency of biological tissues. All compounds are capable of releasing NO⋅ under irradiation, which leads to promising applications in TPA-based drug delivery.

Properly designed molecular rotors with sizable stators and a fast-moving rotator could provide efficient building blocks for amphidynamic crystals. Herein, we report the synthesis of steroidal compounds 1, 2, and 3 and their deuterated analogues 1D, 2D, and 3D envisioned to work as molecular rotors. The obtained compounds were characterized by attenuated total reflection-infrared, Raman, and circular dichroism (CD) spectroscopy measurements. The interpretation of spectra was supported by theoretical calculations using density functional theory methods. The analysis of the most characteristic bands confirmed different molecular dynamics of the rotors investigated. Angle-dependent polarized Raman spectra showed the crystallinity of some samples. Electronic CD (ECD) spectra of compounds 1–3 and their relevant deuterated analogues 1D–3D are identical. The increase of the band intensity with lowering the temperature shows that the equilibrium is shifted to the thermodynamically most stable conformer. ECD spectra simulated at the TDFFT level of theory for compound 3 were compared with experimental results. It was proved that conformer 3a, with a torsion angle of +50°, exhibits the best agreement with the experimental results. Simulated vibrational CD and IR spectra for conformer 3a and its deuterated analogue 3Da also display good agreement with experimental results. In light of our comprehensive investigations, we evidenced that steroidal compounds 1, 2, and 3 can work as molecular rotors.

International audience; We report herein a molecular engineering strategy based on the design of a multipolar ruthenium–nitrosyl (Ru–NO) complex with a three-branched architecture. The three Ru–NO units are introduced at the periphery of a highly π-delocalized truxene core bearing three terpyridine ligands. The two-photon absorption capabilities of the complex were investigated by the Z-scan technique. The strong electronic coupling among the individual arms gives rise to a very strong two-photon absorption response (δ800 nm ∼ 1600 GM), which corresponds to a 16-fold enhancement of the capability of a single-arm reference, thereby promoting an efficient light-driven NO release process in aqueous media.

Two, acyclic (1) and cyclic (2), steroidal molecular rotors containing 1,4-diethynyl-2,3-difluoro-phenylene units as rotators were investigated by means of single crystal X-ray diffraction, high re...

The early detection of cancer cells and their visualization before and after surgery are essential for successful pre‐ and post‐operative disease management. Although fluorescence imaging is a sensitive and versatile tool that is finding increasing use in clinical applications, there is a lack of tumour‐targeting fluorophores. We report here a family of fluorescent Schiff base organotin dyes (1: Et2N−L‐SnPh2, 2: Et2N−L‐SnBu2, 3: MeO−L‐SnPh2, 4: MeO−L‐SnBu2, 5: HO−L‐SnPh2, and 6: HO−L‐SnBu2, where L=2‐hydroxybenzylidene‐4‐hydroxybenzhydrazine). In addition to one‐photon‐excited fluorescence, efficient two‐photon excitation was demonstrated in compounds 1–4. Two of the compounds (5 and 6), both with hydroxyl substituents, were capable of selective accumulation in HeLa cells, allowing differentiation from normal cells (periodontal ligament cells). Compounds 1 and 3 showed excellent cancer cell staining (HeLa) using two‐photon bioimaging, which is promising for biomedicine applications.

Las técnicas espectroscópicas son una herramienta poderosa para la elucidación estructural, en particular, la RMN es una de las espectroscopias más versátiles. En este capítulo se presenta una breve descripción del análisis espectral, seguido de algunos ejemplos tomados del trabajo de investigación de grupo. El énfasis es mostrar la importancia de la RMN para resolver problemas químicos.

Spodoptera frugiperda J.E. Smith (Lepidoptera: Noctuidae) is a polyphagous insect pest native to America. Due to its capacity for adaptation and migration, it is currently located in Africa, Asia, and Oceania, where it threatens agricultural crops. The ability of S. frugiperda to develop resistance to insecticides is one of the reasons for the continuous search for more effective, low-cost, and environmentally friendly control products. In the present work, the insecticidal activity of ethanolic and hexane extracts obtained from fresh and dehydrated leaves of Piper auritum Kunth (Piperales: Piperaceae), Piper umbellatum L. (Piperales: Piperaceae), and Cedrela odorata L. (Sapindales: Meliaceae) was studied against first instar larvae of S. frugiperda. The ethanolic extracts of the dehydrated leaves of C. odorata and P. auritum presented insecticidal activity as high (100% mortality at a concentration of 92 mg/cm2) as that obtained with the positive control, Melia azedarach L. (Sapindales: Meliaceae). The GC-MS analysis of the extracts revealed the presence of phytochemicals classified mainly into the groups of monoterpenes, sesquiterpenes, diterpenes, phenylpropanoids, alcohols, and fatty acids. P. auritum grows and propagates rapidly. In addition, due to its low toxicity in mammals and non-target insects, it is a plant with the potential to be used as a botanical insecticide. The exposure of S. frugiperda larvae to low concentrations of ethanolic extract of P. auritum allowed us to observe their biological activity in the development of this insect. The LC50 was 22.1 mg/cm2. At sublethal concentrations (LC21 and LC35) the low fertility of the emerging adults was noticeable.

Due to their capability for sensing changes in viscosity, fluorescent molecular rotors (FMRs) have emerged as potential tools to develop several promising viscosity probes; most of them, however, localize non-selectively within cells, precluding changes in the viscosity of specific cellular microdomains to be studied by these means. Following previous reports on enhanced fluorophore uptake efficiency and selectivity by incorporation of biological submolecular fragments, here we report two potential BODIPY FMRs based on an ethynylestradiol spindle, a non-cytotoxic semisynthetic estrogen well recognized by human cells. A critical evaluation of the potential of these fluorophores for being employed as FMRs is presented, including the photophysical characterization of the probes, SXRD studies and TD-DFT computations, as well as confocal microscopy imaging in MCF-7 (breast cancer) cells.

The synthesis, characterization, and crystal structure analysis of five new steroidal molecular rotors constructed from two different building blocks, viz., mestranol, ethynylestradiol, levonorgest...

Four dinuclear organotin halides of composition XnPh(3–n)SnCH2Si(Me)2–C12H8–Si(Me)2CH2SnPh(3–n)Xn (X = Cl, I; n = 1, 2) were prepared and combined in 1:1 stoichiometric reactions with potassium 2,5...

A family of pentacoordinated diorganotin(IV) compounds was synthesized and characterized through the advantageous approach of a multicomponent methodology involving the reaction between 4-(diethylamino)salicylaldehyde, dibutyltin oxide and including a series of l -amino acid fragments (alanine, valine, leucine, isoleucine, phenylalanine, tyrosine and methionine), all carried out in one-step, in excellent yields. Structures were elucidated by FTIR, HRMS and solution NMR (1H, 13C and 119Sn). Diorganotin(IV) derivatives crystallized easily and five unreported molecular structures were solved and analyzed by SC-XRD experiments; depending on the orientation of the alkyl residues different isomorphic arrays were found. Finally, pentacoordinated diorganotin(IV) complexes were tested against tumoral cell lines, HCT-15 (colon adenocarcinoma), HeLa (cervical uterine adenocarcinoma), MCF-7 (breast adenocarcinoma) and PC-3 (human prostate cancer) in order to evaluate their in vitro cytotoxicity.

International audience; Using the compound [RuII(FT)(bipy)(NO)](PF6)3 (FT is the electron‐rich 4’‐(2‐fluorenyl)‐2,2’:6’,2’’‐terpyridine ligand and bipy is 2–2’bipyridine) as a reference, two new compounds are presented in which carbon‐carbon double and triple bonds are inserted between the fluorenyl substituent and the terpyridine to provide an extended conjugation path. The electronic properties of the three complexes are compared experimentally by UV‐visible spectroscopy and computationally by means of the density functional theory. All of them exhibit a capability for NO release under irradiation on their low‐energy transition located in the 400–500 nm range, with a quantum yield around 0.01. Their two‐photon absorption (TPA) cross sections are investigated by the Z‐scan technique at λ=800 nm. While the reference compound exhibits a cross‐section equal to 108 GM, the introduction of double and triple bonds leads to increased cross‐sections equal to 131 GM and 150 GM, respectively. These values are discussed in reference to the two‐level model in use for “push‐pull” dipolar TPA chromophores.

A family of eight π-extended push–pull coumarins with cross-conjugated (amide) and directly conjugated (p-phenylene, alkyne, alkene) bridges were synthesized through a convergent strategy. Using an experimentally calibrated computational protocol, their UV–Visible light absorption and emission spectra in solution were investigated. Remarkably, amide-, alkyne- and alkene-bridges undergo comparable vertical excitations. The different nature of these bridges manifests during excited-state relaxation and fluorescence. We predict that these molecules can serve as building blocks for p-type semiconductors with low reorganization energies, below 0.2 eV. Since solid-state self-assembly is crucial for this application, we examined the effect of the π-bridge over the supramolecular organization in this family of compounds to determine if stacking prevails in these π-extended coumarin derivatives. Amide and alkyne spacers allow coplanar conformations which crystallize readily; p-phenylene hinders planarity yet allows facile crystallization; alkene-bridged molecules eluded all crystallization attempts. All the crystals obtained feature dense face-to-face π-stacking with 3.5–3.7 A interlayer distances, expected to facilitate charge transfer processes in the solid state.

International audience; New aza-BODIPYs with significant bathochromic shifts in their UV–vis absorption spectrum were synthesized by the installation of 1-ethyl-indol-3-yl moieties at the 1,7-positions of the aza-BODIPY core bearing 4-substituted phenyl or thien-2-yl groups at the 3,5-positions. The compounds described herein show strong NIR absorptions up to 779 nm, and emissions up to 805 nm in chloroform solution, and present large molar extinction coefficients. The absorption and emission bands of aza–BODIPYs were significantly red-shifted, by ca 100 nm, relative to the 3,5-dianisyl-1,7-diphenyl aza-BODIPY. TD-DFT calculations indicate an effective electronic conjugation between the aza-BODIPY core and the substituents. Absorption of the studied aza-BODIPY derivatives corresponds to a charge transfer from donor substituents toward the boron-centered core. Moreover, computational results show that all the compounds present HOMO–LUMO band gap values that are in the organic semiconductor range.

The dianionic aza crown ether-dtc N,N'-bis(dithiocarbamate)-1,10-diaza-18-crown-6 (L2-) is a versatile ligand capable of yielding binuclear complexes with group 10 elements, also known as Ni-triade, [μ-(κ2-S,-S'-L)M2(PPh3)4]Cl2 (M = Pd (1), Pt (2)), [μ-(κ2-S,-S'-L)M2(PPh3)4](BPh4)2 (M = Pd (3), Pt (4)), and μ-(κ-S,-S'-L)Ni2(PPh3)2Cl2 (5), and has proven to be an excellent option to the design of metal-based drugs able to provide multiple response to cell resistance. Palladium and platinum complexes, 1 and 2, were tested for cytotoxicity in the human cervix carcinoma cell line HeLa-229, the human ovarian carcinoma cell line A2780, and the cisplatin-resistant mutant A2780cis, finding significant activity toward all three cancer cell lines, with low micromolar IC50 values, comparable to cisplatin. Markedly, against the cisplatin resistant cell line A2780cis, compound 2 exhibits better cytotoxic activity than the clinical drug (IC50 = 2.3 ± 0.2 μM for 2 versus 3.6 ± 0.5 μM for cisplatin). Moreover, an enhancement of the antitumor response is achieved when adding an equimolar amount of alkali metal chloride (NaCl or KCl) to the medium, for instance, testing compound 1 against the cisplatin-resistant A2780cis cells, the IC50 decreases from 9.3 ± 0.4 to 7.4 ± 0.3 and 5.4 ± 0.1 μM, respectively, after addition of the salt solution. For the platinum derivative 2, the IC50 improves by ca. 40% reaching 1.3 ± 0.1 μM when potassium chloride is added. Likewise, the resistant factor found for 2 (RF = 1) confirms that this complex circumvents cisplatin-resistance in A2780cis and is improved with the addition of potassium chloride (RF = 0.65). The presence of the aza crown ether moiety as linker in the systems studied herein is a key point since, in addition to allowing and facilitating interaction with alkali metal ions, this unit is flexible enough to adapt to a variety of environments, as confirmed by the X-ray crystal structures described, where different conformations and ways to fold in are found. In order to gain insight into the electronic and structural facts involved in the interaction of complex 2 with the alkali metal ions, a DFT study was performed, and the description of the molecular electrostatic potentials (MEPs) is also presented.

International audience; A series of electronic and physicochemical parameters were explored to determine their effect on experimental spectroscopic and photophysical data. Through a systematic obtention of a series of meso-(o-aryl)-BODIPYs, 19F NMR spectra were analyzed and their fluorescence quantum yields in several solvents were measured. Experimental values of 19F chemical shift difference ΔδF correlate well with σ-Hammett constants, which is indicative of the inductive nature of the functional groups on the fluorine atoms. A computational DFT exploration of rotational energy barriers, electrostatic potential maps, group electronegativity, charge partitions and hardness/softness provided insight into how those traits can be directly related to the measured features. Expanded understanding of such characteristics provides design arguments and a structure–property relationship, which in a more advantageous way, would help to understand the properties of the synthesized molecules and of future attempts that are structurally related.

In this work, we evaluated the antiproliferative and anti-inflammatory activities of two diosgenin prodrugs. The prodrugs were obtained by esterification of diosgenin at position 3 with 4-oxo-4-(prop-2-yn-1-yloxy)butanoic acid followed by click reaction on terminal alkyne with 3-azidopropan-1-ol N-alkylated dendrons, resulting in a prodrug with methyl ester end-groups and a derivative with tert-butyl ester end-groups, hydrolysis of tert-butyl ester derivative afforded a prodrug with carboxylic acid terminals. All compounds were fully characterized by 1H and 13C NMR, ATR-FTIR and HR-ESI TOF. Studies of the anti-inflammatory effects on mouse ear edema of prodrugs methyl ester and carboxylic acid, ended, using diosgenin and dexamethasone as positive controls, showed the superiority of methyl ester ended prodrug with an ED50 four times lower than that of dexamethasone. Further, carboxylic acid ended prodrug was found to be more active than diosgenin as an antiproliferative agent, according to crystal violet assay. Diosgenin was transformed to ester and acid prodrugs through succinic ester and a 1,2,3-triazole linkers. The prodrug with methyl ester terminals was four times more active than dexamethasone as anti-inflammatory compound, while prodrug with carboxylic acid terminals improved antiproliferative activity over MCF-7 cells.

Delving into the scarcely explored versatility and selectivity of 4,7-dibromo-[1,2,5]thiadiazolo[3,4-c]pyridine towards aromatic nucleophilic substitution, eleven new compounds were synthesized using different nucleophiles (alcohols, amines, and thiols). The compounds described herein allow us to get a glimpse of important building blocks for the synthesis of biologically attractive molecules and for organic materials or species with fluorescence properties. Given the structural diversity of the electron-donating substituents, the effect of the functional groups introduced was studied through a tandem experimental-theoretical approach to analyze the electronic properties bestowed on the TDAP core. Insights into the selectivity towards a single position and the differences between nucleophiles were achieved through a DFT analysis of the energetics of the reactions performed.

The synthesis and characterization of a new Carbonic dihydrazide, bis[2-(hydroxyimino)-1-methylpropylidene] is described. The compound was characterized by NMR (1H, 13C), high-resolution mass spectrometry and X-ray diffraction. We observed the ligand with anti-trans conformation in solid state and symmetric (C2) conformer in solution. The relative energies of the conformers were calculated, using the density functional theory (DFT) to determine their relative stability. Both the single-crystal and calculated structures indicate that the asymmetric conformer is the most stable conformer in the absence of solvent.

Local microviscosity monitoring in living cells is a powerful tool to determine their healthy status in either a specific organelle or in the cytosol. Here is presented the rational design of a new family of self-calibrating dual-microviscosity probes as a strategy to improve the probe response at low viscosity ranges. We found one of the probes is useful to determine low viscosity variations in living cells where subtle stiffening of the rotor group in the probe can increase its viscosity sensitivity. Further X-ray structure analysis, fluorescence anisotropic measurements, and quantum chemical calculations of the electronic excitation by means of a natural transition orbital (NTO) analysis confirmed the observed response. The present work demonstrates that small viscosity variations (0.01–0.1 cP) in cells require improved analytical sensitivity to be properly monitored.

In this work, a rapid, efficient and protecting group free diastereoselective synthesis of propargylamines through a multicomponent coupling reaction between (S)-prolinol, phenylacetylene and commercially available aldehydes catalyzed by Cu-MCM-41 in heterogeneous phase is reported. The reactions were carried out under solvent free conditions with good yields and moderate reaction times. In all the cases, catalyst was recovered and reused up to five cycles. Recyclability of the catalyst, low catalyst loading, solvent and protecting group free conditions, and the use of inexpensive catalyst are the key features that provide green aspects to this synthetic protocol.

Two molecular rotors featuring pyridine and fluorobenzene rings as polar rotators and 9-octylfluorenyl stators were synthesized. Their crystal structures were established through SXRD techniques, crystallizing in the monoclinic chiral P21 space group. The supramolecular assemblies of both isomorphs showed an orientation of static dipoles through the crystal lattice and the formation of intriguing 2D layers that resemble cell membranes, a typical example of an amphidynamic system. Small activation energies and the modulation of the first-order hyperpolarizabilities of these compounds as a function of rotational dynamics were revealed through DFT computations at the CAM-B3LYP/M06-2X/cc-pVDZ level of theory and correlated with a potential use of these materials as photonic switches.

A series of five 2-(2-hydroxyphenyl)oxazolo [4,5-b]pyridines (HPOP) (3a-e), where four are novel, were synthesized by a mild, one pot, phenylboronic acid-NaCN catalyzed reaction. Spectroscopic characterization and photophysical properties of these compounds are reported. Absorption and excitation spectra of the compounds were dependent on the substituents in the phenyl ring. Fluorescence quantum yields (0.009–0.538) were associated with the donor strength and the position of the substituents. Also, DFT analysis allowed us to determine the contribution of diethylamino and methoxy moieties to the π-system, which is in agreement with the experimental data analyzed in solution and by cyclic voltammetry. The results obtained in the solid state by single-crystal X-ray diffraction experiments indicate that, the quasi-planarity envisioned for the explored compounds is present, supporting the hypothesis that both the H-bonding of a hydroxyl group to the C N moiety and a donor groups such as diethylamino and methoxy moieties favor an electronic communication. Due to the facile synthesis and their photophysical properties, the novel HPOP 3a-e have potential application as organic semiconductors.

In this work, we report the synthesis of a novel carbohydrate-lithocholic acid conjugate linked through of 1,2,3-triazole rings and its derivatives in good to excellent yields. The conjugate was synthesized via copper-catalyzed azide−alkyne cycloaddition (CuAAC) from methyl 4,6-O-benzylidene-2,3-di-O-propargyl-α- d -glucopyranoside and methyl 3-azidolithocholate. The structures of all new compounds were properly characterized by infrared (IR), high-resolution mass spectroscopy (HRMS) and one- and two-dimensional nuclear magnetic resonance (NMR).

The synthesis and characterization of acyclic and cyclic molecular rotors with 1,4-diethynylphenylene-d4 rotators are described. The ATR-FTIR and Raman spectra of acyclic rotor 3 and cyclic rotor 5E were measured and interpreted. A feature of ATR-FTIR spectrum of rotor 5E is a strong two-component band around 1730 cm− 1 attributed to symmetric and asymmetric stretching vibration of the carbonyl group, while this is not observed in rotor 3. Raman investigation in the wide temperature range of 350 - 10 K was carried out. The splitting of Raman bands in the region of stretching vibration of CC double and triple bonds at 170 and 260 K for rotor 5E is observed. The splitting of bands is due to changes in molecular structure.

Four BTD-derivatives 4 , 5 , 7 and 8 were synthesized and characterized by using solution NMR, FTIR and HRMS. In this study, BTD-central cores were supported on trityl type fragments in order to evaluate the influence of these groups prone to aggregation through interdigitation in the consolidation of ordered solids. Structural variation, between compounds 4–5 and 7–8, was selected by introducing aromatic phenyl rings at positions C-4 and C-7 of the BTD central core in order to increase the stackable surface. Crystals of compounds 4 and 5 were obtained and solved in the C 2/ c and P 2 1 / c space groups, respectively. Both crystalline arrays are dominated by C H⋯π and π-stacking interactions, desirable features for the bottom-up construction of highly polarizable organic crystals. The featured compounds with a dumbbell-like structure could be useful as scaffolds for self-assembled crystalline materials such as solid organic semiconductors.

Poly(vinyl alcohol) (PVA) is a linear polymer of synthetic origin, biocompatible and inert, representing a good starting point to incorporate dendrons and potentiate their ability to act as drug-carrier releasers. This article reports the synthesis of G 1.5 PAMAM-type dendrons from propargylamine with methyl or tert-butyl ester end groups. Subsequently, these dendrons were grafted into PVA functionalized with azide groups (N3) through a click reaction. Dendron-grafted PVA showed different chemical and physical properties to those of PVA and azidated PVA, since PAMAM-type dendrons modified the molecular interactions between the different polymer chains and with the medium, resulting in changes in hydrodynamic radius (Rh) density, solubility, and glass transition temperature. Compared with PVA and azidated PVA, the grafting of methyl ester ended dendrons afforded a 94% water-soluble material at room temperature, with a decrease in its density and an increase in its Tg, while in the case of the tert-butyl ester ended dendrons only 69% of the material is water-soluble, and it presented the lowest density and the lowest Tg due to increasing in free volume. The Rh values of dendron-grafted PVA increased according to molecular weight. The obtained products were characterized by ATR-FTIR, UVvis, and/or NMR (1H, 13C).

Two new fluorescent organotin compounds bearing C3-symmetric Schiff base were synthesized by microwave irradiation via multicomponent reaction (3-MCR), in one pot in just 30 mins with excellent yields. Both tin complexes were fully characterized by NMR, IR, UV-vis, fluorescence spectroscopy, high-resolution mass spectrometry and by ciclyc voltametry. The δ 119Sn and 3J(1H,119Sn) of new organotin complexes 4 and 5 showed the high molecular symmetry and the trinuclearity through high resolution mass spectrometry. Both Sn-complexes are thermally stable up to 300°C. The small-wide angle X-ray scattering pattern in powder and the 2D monomolecular film by scanning tunneling microscopy (STM) of 5 showed a lamellar like assembly with dimension of 2.38 and 2.80 nm, respectively, meaning that molecules adopt a face-on arrangement, where molecules are flat-lying on the HOPG surface. Monolayer of 5 is mesoporous and rigid but covers large surface areas. The photophysical, electrochemical, and theoretical studies reveal that the three Sn-nuclei do not electronically interact. Since, both organotin complexes exhibit good quantum yield in solution (Φ 4: 52.4 % and 5: 51.7 %), with lifetimes in the range τ =∼3 ns, their emission properties are appealing for OLED applications.

In Peru, until the beginning of 2016, foods with upcoming expiration dates, even though in good condition, did not go on sale to the public, nor donated to entities such as food banks, this because both operations were considered by the Peruvian Income Tax Law as sales in a strict sense, that is, in the light of Peruvian law they are taxed operations. In this sense, in order to recover some of the expenditure incurred in the purchase of such food, the companies had to destroy food, a measure opposed to rational economic logic, as well as compliance with the Sustainable Development Goals (SDG). At the end of 2016, a tax reform was approved, which included the creation of a tax deduction for food donation. This paper analyzes the effects of said norm, taking as a reference the Colombian proposal contained in the so-called “Anti-food Waste Law to Fight Hunger in Colombia”. The objective of this paper is to determine if the tax benefits of the Peruvian regulations function effectively as an incentive mechanism for food donation in supermarkets located in the Metropolitan Area of Lima. The present research work uses a qualitative and quantitative approach, of descriptive - explanatory type from the comparison of normative frameworks, with which it is sought to clarify the fiscal and parafiscal scope of the indicated tax norm in Peru and its impact in pro of social development and the effects it has as a social responsibility measure. En Perú, hasta inicios de 2016, los alimentos con fechas próximas de vencimiento, a pesar de que se encontraran en buen estado, no salían a la venta al público ni tampoco eran donados a entidades como bancos de alimentos; esto porque ambas operaciones eran consideradas como operaciones gravadas. En ese sentido, las empresas con el fin de poder recuperar algo del gasto en el que incurrieron en la compra de dichos alimentos debían destruirlos, una medida opuesta a una lógica económica racional, así como al cumplimiento de los Objetivos de Desarrollo Sostenible (ODS). El objetivo de este trabajo fue determinar si los beneficios de la reforma tributaria peruana de 2016 funcionaron de manera eficaz como mecanismo de incentivo para la donación de alimentos en los supermercados que se encuentran en al área metropolitana de Lima, Perú. Para esta investigación se empleó un enfoque mixto, de tipo descriptivo-explicativo a partir de la comparación de marcos normativos, con el cual se buscó clarificar los alcances fiscales y parafiscales de la indicada norma tributaria en el Perú y su impacto en pro del desarrollo social y los efectos que tiene como medida de responsabilidad social.

Four organotin compounds bearing Schiff bases were prepared via a multicomponent microwave-assisted reaction among 2-hydroxy-1-naphthaldehyde, 2-aminophenol derivatives and the corresponding diorganotin oxide (R2SnO, R = nBu or Ph), with high yields and a low economic/environmental impact. All of the compounds were fully characterized by NMR (1H, 13C, and 119Sn) spectroscopy, high-resolution mass spectrometry, X-ray diffraction, cyclic voltammetry, UV/Vis spectroscopy, and fluorescence spectroscopy. All of the compounds absorb in the visible region around 480–490 nm, close to the maximum solar emission, with an optical band gap of around 2.3 eV and low fluorescence quantum yields. According to the electrochemical study, they present LUMO values close to that of [6,6]-phenyl-C61-butyric acid methyl ester (PCBM-C60), a typical electron acceptor organic photovoltaic material. Based on this combined optical/electrochemical study and as it allows the preparation of homogeneous spun films, the n-butyltin complex with carboxylic acid was selected for the investigation of its possible photovoltaic properties in organic solar cells. Charge photogeneration was obtained only using this organotin compound as an electron acceptor material with poly(3-hexylthiophene, P3HT) (typical electron donor material) with an open circuit voltage of 300 mV, a short-circuit current density of 0.11 mA cm−2 and an efficiency of 5.2 × 10−3%. Despite the fact that the efficiency is much lower with respect to the reference device P3HT/PCBM-C60, this preliminary result suggests that, after chemical and device processing optimization, tin complexes with Schiff bases could be applied as electron acceptor materials in organic photovoltaic devices.

International audience; In this paper we report the synthesis and characterization of four novel pentacoordinated diorganotin complexes, obtained through a methodology that involves a multicomponent reaction of 4-([9H-fluorene-2-yl]ethynyl)-2-hydroxybenzaldehyde, 2-amino-5-nitrophenol and diphenyl or dibutyl-tin oxides. Diorganotin complexes 8–11 were obtained in high yields (70–80%) and were fully characterized by solution NMR (1H, 13C and 119Sn), high resolution mass spectrometry (ESI-TOF) and ATR-FTIR. The optical properties were investigated by UV/Vis spectroscopy and Two-Photon Excitation Fluorescence (TPEF). The One-Photon Absorption (OPA) spectra shows two bands located around 400 and 500 nm, additionally, in the Two-Photon Absorption (TPA) spectra there is one main band located around 750 nm characterized by maximum values of TPA cross section (σTPA) in the range 450–500 GM with a secondary band located at 1000 nm with maximum σTPA values of 70 GM; the maximum brightness was observed for 2,2-Dibutyl-6-aza-1,3-dioxa-11-([9,9-dihexyl-9H-fluorene-2-yl]ethynyl)-16-nitro-2-stanna-[d,h]dibenzocyclononene with a value of 150 GM. A theoretical approach within the framework of DFT was applied to study the electronic transitions, showing that the 500 nm band is mainly associated to a HOMO→LUMO transition, and the band at 400 nm to a HOMO-1→LUMO transition. As main highlights the quantum efficiency of fluorescence of these excited states is as large as 0.43 due to the presence of the tin atom which favors molecular rigidity, these compounds possess TPA responses which are significantly enhanced with respect to related organotin chromophores previously reported.

Chagas disease is a health problem that affects millions of persons, currently Nifurtimox (Nfx) and Benznidazole (Bz) are the unique drugs to treat it. However, these drugs produce adverse effects and high toxicity, which has motivated the search for new candidate drugs. Based on reports about the extensive biological activity of steroidal nitrate esters, in this study three nitrate esters steroids (1b, 2b and 4b) were synthetized and characterized from Dehydroepiandrosterone (DHEA, 1a), 19-hydroxy-DHEA (2a), and Androst-5-en-3β,17β-diol (4a), respectively. In addition, compounds 3a and 3b were obtained by introducing an α-ethynyl and a β-hydroxyl groups at position 17 of 2b and further nitration of the hydroxyl group. The trypanocidal activity of these steroids was evaluated in vitro against the epimastigote stage of two T. cruzi strains, Ninoa and TH, and their cytotoxicity over J774.2 macrophage cell line was assayed. Compounds 3a, 3b, and 4a shown higher trypanocidal activity than Bz and Nfx against epimastigotes of Ninoa strain, whereas DHEA (1a) and its nitrate derivative 1b showed higher activity than the reference drugs against the TH strain epimastigote. None of the compounds showed activity in the ex vivo assays against the blood trypomastigote of both strains. Interestingly, the selectivity index of Androst-5-en-3β,17β-diol 4a was almost twice the value of Nfx and 50 times more than Bz, against Ninoa and TH strains, respectively. Therefore, compound 4a could represent a valuable starting point toward the optimization of steroid derivatives as trypanocidal agents.