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In the search for photoluminescent carbo-benzenes, with the view to measuring the two-photon absorption cross-section by the TPEF method, thienylbenzothiadiazole groups are envisaged as intrinsic fluorophoric substituents through acetylenic linkers.

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...

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.

A new dibrominated 4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) is reported as a new metal-free photocatalyst. This BODIPY showed similar optoelectronic, electrochemical, and performance properties to those of Ru(bpy)3Cl2, one of the most common photocatalysts in a known radical-ionic transformation, such as the formation of 1,4-dicarbonyl compounds. Moreover, additional sequences in which the generated oxonium ion is trapped by an internal nucleophile were developed using this BODIPY photocatalyst. These new sequences allowed the straightforward preparation of γ-alkoxylactones, monoprotected 1,4-ketoaldehydes, and dihydrofurans. This new catalyst, the methodology, and the forged functional groups could be important tools in organic synthesis.

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.

Two crystalline meso-substituted BODIPYs were investigated as supramolecular building blocks of Langmuir–Blodgett (LB) thin films. These sorts of thin films are formed by the transfer of a Langmuir monolayer film of organized amphiphilic molecules onto a solid substrate. In the present contribution, we exploited the capacity of the featured BODIPYs to produce ordered supramolecular self-assemblies through hydrogen-bonding and π-stacking to pre-organize and to control their assembly as LB thin films. Electronic absorption and fluorescence emission of the meso-substituted BODIPYs in solution, LB films, and in solid state were studied. The morphology and structure of the LB films were examined by scanning electron microscopy and atomic force microscopy. The structural differences between both BODIPYs have no marked influence on the absorption and fluorescence emission properties in solution. In contrast, absorption properties in solid state (solid samples and LB thin films) depend on the structural nature of the dyes with the appearance of red-shifted bands, which could be an indicator of the presence of aggregates. The supramolecular information contained in the BODIPYs was reflected on the surface characteristics of the featured LB thin films. Both produced homogeneous and uniform films with the presence of some microcrystals, as the number of transferred monolayers increased. These results broaden the capacity of the Langmuir–Blodgett technique to produce ordered and self-assembled thin films of functional small organic molecules (such as BODIPYs) as components of different optoelectronic devices.

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

The electrochemical reduction of two meso-substituted dipyrrometheneboron difluorides, BODIPYs, 8-(thiophen-2-yl)-dipyrrometheneboron difluoride and 8-(phenyl)-dipyrrometheneboron difluoride, was studied in acetonitrile. Both compounds underwent two consecutive electron transfers to produce the radical anion and dianion species. The cyclic voltammograms show that the current intensity of the second cathodic peak is much smaller than the first one-electron reduction process. The current intensity ratio of the two peaks (iIIc/iIc) was analyzed as a function of the BODIPY concentration and of the scan rate; the results indicate that dimerization reactions are responsible for the remarkable current decrease in the second electroreduction. Digital simulations of the experimental cyclic voltammograms show that the three possible dimerization reactions, radical anion-radical anion, radical anion-dianion and neutral-dianion, have a different effect on the voltammetric behavior. Thus, the simulation analysis allowed to elucidate the reaction mechanism.

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.

In this work, the influence of carbon dioxide on the synthesis of palladium nanoparticles (PdNPs) in glycerol/ionic liquid mixtures and their further applications in catalytic hydrogenations was st...

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.

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 nanostructured alloys of the Pd–Ag system have shown outstanding properties due to the synergistic effects of the alloying; additionally, it is a system that meets very well the Hume–Rothery rules for alloys formation and hence, shows complete miscibility at all compositions, especially at the nanoscale. Consequently, several synthetic routes have been already explored. In this work a novel and relatively low cost mechanochemical synthetic route to obtain nanoparticles of this bimetallic system is presented. The entire characterization suggests the formation of a nanostructured alloy in all samples, as well as, the lack of segregated pure metals. Suzuki–Miyaura cross-coupling reaction was used as model reaction in order to evaluate the catalytic activity of the synthesized Pd100-xAgx alloys, which have behaved as an excellent heterogeneous ligand-free catalyst. The reaction can be achieved under mild conditions, with low catalyst loadings; these catalysts also maintained most of their activity after successive catalytic cycles with high yields. Furthermore, the observed activity seems to be due not only to Pd content, but to the nanoalloy is having a role in the catalytic process. Therefore, the cost of the catalytic reaction could be reduced by using PdAg nanoalloys.

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.

A series of novel fluorescent BODIPY-anionic boron cluster conjugates bearing [B12H12]2– (5, 6), [3,3′-Co(1,2-C2B9H11)2]− (7, 8), and [3,3′-Fe(1,2-C2B9H11)2]− (9) anions have been readily synthesized from meso-(4-hydroxyphenyl)-4,4-difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY 4), and their structure and photoluminescence properties have been assessed. Linking anionic boron clusters to the BODIPY (4) does not alter significantly the luminescent properties of the final fluorophores, showing all of them similar emission fluorescent quantum yields (3–6%). Moreover, the cytotoxicity and cellular uptake of compounds 5–9 have been analyzed in vitro at different concentrations of B (5, 50, and 100 μg B/mL) using HeLa cells. At the lowest concentration, none of the compounds shows cytotoxicity and they are successfully internalized by the cells, especially compounds 7 and 8, which exhibit a strong cytoplasmic stain indicating an excellent internalization efficiency. To the best of our knowledge, these are the fi...

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 2:1 fluorinated arylboronic ester adducts with 4,4′-bipyridine sustained by N→B dative bonds have been synthesized. The degree of fluorination in the arylboronic esters derived from catechol is shown to modulate the molecular conformation of the coordinated boronic ester moieties and the intermolecular interactions by means of C–H···F and F···F contacts that sustain the crystal lattices. The adduct derived from the catechol ester of 2,4-difluorophenylboronic acid was chosen to examine the formation of inclusion complexes with a large number of aromatic guests, affording solvates, cocrystals, and a cocrystal solvate. Six different crystal structure types with 1:1, 1:2, and 1:2:2 N→B adduct–guest ratios were observed, whose supramolecular organization is strongly influenced by the formation of sandwich-type complexes between the host and guest molecules. The host–guest interactions involve π···π interactions with the bipyridine linkers and additional contacts with the catecholate and B-arylF sub...

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.

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).

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.

Chromophoric coumarin-BODIPY derivatives bridged by an ethynyl π-bridge were investigated as supramolecular building blocks of organic semiconducting solids through X-ray analysis, UV/Vis and fluorescence measurements, and quantum chemical calculations of the frontier orbital energy depending on the chemical environment. Based on a push-pull architecture, the molecular properties of 7-(diethylamino)coumarin core end-capped with BODIPYs as well as the supramolecular self-assembly can be directed through the modification of the ethyny-aryl π-bridge and the intermolecular interactions it generates. Frontier orbital energy changes depending on chemical environment were performed, in particular, upon adsorption on a flat semiconducting surface. Coumarin-BODIPY building-blocks self-assemble into molecular crystals and highly-ordered thin-films with desirable periodic π-stacking interactions for semiconducting applications. The present work represents a convenient alternative to engineer organic semiconducting solids based on coumarin-BODIPY systems for organic electronics.

The molecular structure of 1-[2-oxo-2-(2-pyridinyl)ethyl]pyridinium iodide (C12H11IN2O) is discussed using an experimental (FT-IR/ATR, NMR, SXRD) and theoretical (DFT, B3LYP/6-311G**) approach. Compound 2 crystallized in the monoclinic P21/c space group with 4 molecules per unit cell and unit cell dimensions a = 7.5629 A (3), b = 21.5694 A (7), c = 7.8166 A (3). The crystal packing is governed by ion-dipole contacts and π-π stacking. High electrostatic potential at the ethanone hydrogens was derived from DFT calculations, further explaining the acidity and reactivity of the molecule as a Michael donor.

We report the design, synthesis, and characterization of two new fluorescent molecular rotors of boron derived from Schiff bases: (2,4,8,10-tetra-tert-butyl-6-phenyldibenzo[d,h][1,3,6,2]dioxazaboronine (3) and 1,4-bis(2,4,8,10-tetra-tert-butyldibenzo[d,h][1,3,6,2]dioxazaboronin-6-yl)benzene (4), as well as the free ligand 2-[[(3,5-di-tert-butyl-2-hydroxyphenyl)imino]methyl]-4,6-di-tert-butylphenol 1. All compounds were fully characterized by NMR (1H, 11B, and 13C), IR, UV/vis, fluorescence spectroscopy, and high-resolution mass spectrometry. The crystal structures of 3 and 4 showed tetracoordinated boron atoms with semiplanar skeleton ligands. The free rotation of the fluorescent molecular rotor, only observed in the binuclear compound, was decreased with increasing viscosity, while the quantum yield was increased. Interestingly, the property of reversible thermochromism was found in organoboron 4 in the solid state. DFT calculations to determine the both complexes have free rotation around the CPh–B1 bon...

In this study, a set of molecular crystals derived from 3-substituted-7-(diethylamino)-2H-chromen-2-ones 1–8 were studied to sample the aggregation of coumarins into ordered solids. Crystals of parent compound 1a and its brominated derivative 2 were obtained and solved in the P-1 and C2/c space groups, respectively. All the crystalline coumarins studied display extensive π-stacking in the solid-state. Theoretical valence-conduction band gaps for derivatives 3b and 5 are close to crystalline rubrene, highlighting the importance of cooperativity and periodicity of π-stacking, in organic semiconductors; given their synthetic accessibility, electronic tunability and self-assembly via stacking, dipolar and H-bonding interactions, these systems arise as candidates for the bottom-up construction of organic crystals with extensive π-stacking and high polarizability.

International audience; The synthesis and behavior in water of a set of various cis(Cl,Cl)-[R-tpyRuCl2(NO)](PF6) and trans(Cl,Cl)-[R-tpyRuCl2(NO)](PF6) (R = fluorenyl, phenyl, thiophenyl; tpy = 2,2′:6′,2′′-terpyridine) complexes are presented. In any case, one chlorido ligand is substituted by a hydroxo ligand and the final species arises as a single trans(NO,OH) isomer, whatever the nature of the starting cis/trans(Cl,Cl) complexes. Six X-ray crystal structures are presented for cis(Cl,Cl)-[thiophenyl-tpyRuCl2(NO)](PF6) (cis-3a), trans(Cl,Cl)-[thiophenyl-tpyRuCl2(NO)](PF6) (trans-3a), trans(NO,OH)-[phenyl-tpyRu(Cl)(OH)(NO)](PF6) (4a), trans(NO,OH)-[thiophenyl-tpyRu(Cl)(OH)(NO)](PF6) (4b), trans(NO,OEt)-[phenyl-tpyRu(Cl)(OEt)(NO)](PF6) (5a), and trans(NO,OH)-[phenyl-tpyRu(Cl)(OEt)(NO)](PF6) (5b) compounds. The different cis/trans(Cl,Cl) complexes exhibit an intense low-lying transition in the λ = 330–390 nm range, which appears to be slightly blue-shifted after Cl → OH substitution. In water, both cis/trans(Cl,Cl) isomers are converted to a single trans(NO,OH) isomer in which one chlorido- is replaced by one hydroxo-ligand, which avoids tedious separation workout. The water stable trans(NO,OH)-species all release NO with quantum yields of 0.010 to 0.075 under irradiation at 365 nm. The properties are discussed with computational analysis performed within the framework of Density Functional Theory.

A set of BODIPY‐carboranyl dyads synthesized by a Sonogashira cross‐coupling reaction, where different C‐substituted ortho‐ and meta‐carboranyl fragments have been linked to a BODIPY fluorophore is described. Chemical, photophysical and physicochemical analyses are presented, including NMR and SXRD experiments, optical absorption/emission studies and log P measurements. These studies, supported by DFT computations (M06‐2X/6‐31G**) provide an explanation to the largely divergent cell income that these fluorescent carboranyl‐based fluorophores display, for which a structural or physicochemical explanation remains elusive. By studying the cell uptake efficiency and subcellular localization for our set of dyads on living HeLa cells, we tracked the origins of these differences to significant variations in their static dipole moments and partition coefficients, which tune their ability to interact with lipophilic microenvironments in cells. Remarkably, m‐carboranyl‐BODIPY derivatives with a higher lipophilicity are much better internalised by cells than their homologous with o‐carborane, suggesting that m‐isomers are potentially better theranostic agents for in vitro bioimaging and boron carriers for BNCT., The work has been performed within the framework of the French-Mexican International Laboratory (LIA-LCMMC). Authors acknowledge support from PAPIIT (IN222819) and CONACyT. The work was supported by Spanish Ministerio de Economía y Competitividad, MINECO (CTQ2016-75150-R) and Generalitat de Catalunya (2017/SGR/1720). Doctoral scholarships were granted by CONACyT to P.L.-V (337958) and R. F.-C. (576635). We thank María E. Ochoa (CINVESTAV-IPN), Marco A. Leyva (CINVESTAV-IPN) and Flor R. Vega (FQ-UNAM) for NMR/HRMS experiments, SXRD experiments and technical support, correspondingly.

A series of highly attainable desymmetrized heterocyclic compounds with Donor-Acceptor-Donor-Acceptor-X (D-A-D-X) architectures were synthesized. The structures, where X corresponds to a heteroaromatic portion (pyridine, ferrocene, thiadiazolopyridine), were designed through computational analysis. Molecular geometries for all compounds were studied and parameters of charge transfer were computed in order to analyse the behaviour in each architecture. Spectroscopic properties (maximum absorption wavelengths, extinction coefficients and HOMO-LUMO gaps) were predicted and measured experimentally. UV-Vis absorption profiles and values of HOMO-LUMO optical gaps (in the vicinity of 2.0 eV), together with the computational results, are properties that position the obtained systems, as potential candidates for developing efficient photovoltaic materials based on synthetically accessible small organic molecules.