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This article discusses the synthesis and characterization of a thermally stable monoruthenium acetylide radical species. The researchers examined the reactivity and properties of metal acetylide complexes, specifically focusing on mononuclear ruthenium acetylide radicals. They found that the choice of metal center and ligands significantly influenced the reactivity of these complexes. The researchers were able to isolate and characterize a mononuclear ruthenium acetylide radical species, which exhibited high thermal stability. This study provides insights into the design strategy for controlling the reactivity of radicals in metal complexes. [Extracted from the article]

Graphical abstract Highlights • Redox chemistry of mono- and di-nuclear radical species of Fe and Ru. • Difference of location of the radical center, on the metal centers or on the ligand. • Delocalized dinuclear species may work as molecular wire. Abstract Redox chemistry of d 6 iron(II) and ruthenium(II) complexes has been studied extensively due to the interesting reactivity of mononuclear radical species and the charge-delocalized properties of dinuclear mixed-valence (MV) complexes. In particular, organometallic dinuclear MV systems show long-range charge-delocalized behavior, and their properties can be modified by the choice of the metal (M) and the bridging ligand (BL). Here we review mono- and di-nuclear radical species having CP 2 M and CPM(dppe) fragments (CP = η 5-C 5 H 5 or η 5-C 5 Me 5 ; M = Fe, Ru) as the redox centers. Although the Fe and Ru species are frequently isostructural, the electronic structures of them are considerably different. Radical center tends to localize rather on the metal center and the ligand part in the Fe and Ru complexes, respectively. For mononuclear species, the Ru complexes exhibit reactivity at the ligand to undergo radical coupling, whereas the Fe complexes may stay as monomeric radical species. For dinuclear complexes, the radical center of mixed-valence diiron species rather localizes on the metal center, while that of the diruthenium analogues tends to localize on the BL. The difference could be ascribed to reorganization caused by the electron transfer, and the extent of the contribution of the BL-localized state can be estimated by the difference between the ν max values for an Fe complex and its Ru derivative (Δν max (Ru-Fe)). [ABSTRACT FROM AUTHOR]

Abstract Hexaphenyl- (1) and hexathienyl-benzene (2) complexes with the six redox-active Cp*(dppe)Fe-C≡C- units are synthesized and their properties in terms of molecular junction are investigated. Both complexes show stepwise multi-redox processes and IVCT bands in the NIR region upon progressive oxidation from the neutral to hexacationic state, as a result of intramolecular electron transfer processes via troidal conjugation through the peripheral aromatic rings. Judging from the V ab values obtained by deconvolution analysis, electronic interaction for thienylene derivative 2 turns out to be stronger than that for the phenylene complex 1. DFT analysis of model complexes support superio'r electron transfer properties for the thienyl derivatives. Graphical abstract Image 1 Highlights • Synthesis of hexaphenyl- and hexathienyl-benzene complexes bearing the six peripheral redox-active Cp*(dppe)Fe-C≡C- termini. • Communication between the peripheral iron centers through toroidal conjugation as analyzed by electrochemistry and IVCT bands. • A DFT study of the model complexes supports the stronger toroidal conjugation for the hexathienyl complex. [ABSTRACT FROM AUTHOR]

A rigid tribranched scaffold with three anthracene panels was synthesized using a stereocontrolled 1,3,5-triphenylbenzene core. Grinding a mixture of the rigid scaffold and perylene leads to the quantitative formation of a spherical assembly containing stacked perylene molecules in water. The wrapped perylenes exhibit unusual Y-type excimer-like emission (λmax = ∼500 nm) at room temperature. In contrast, an analogous assembly from a flexible tribranched scaffold and perylene shows E-type emission (λmax = ∼610 nm) from the wrapped perylenes under the same conditions. [ABSTRACT FROM AUTHOR]

Metallophthalocyanines (MPcs) are very useful pigments but scarcely soluble without appropriate functional groups in common solvents. Herein, we report that bent polyaromatic amphiphiles act as excellent solubilizing reagents for nonfunctionalized MPcs and larger MPc derivatives (e.g., CuPc, perhalogenated CuPcs, Cu-naphthalocyanine, CuPc polymers, and double-decker MPcs) in neutral water upon encapsulation. The resultant MPc nanocomposites display high stability towards heat and pH change. More importantly, the encapsulated MPcs can be released by simple protocols under mild conditions both into a bulk solvent and onto glass or polymer plates. [ABSTRACT FROM AUTHOR]

Nanocarbons are synthetic carbon-rich compounds with polyaromatic frameworks that have lately attracted attention as emerging functional materials. However, their extreme hydrophobicity and aggregation peculiarity, besides their shape and size diversities, precluded their study in solution, especially in 'green' water. More convenient and general solubilizing methods of nanocarbon frameworks are required by using non-covalent supramolecular interactions. Here we report a protocol for solubilizing a wide range of nanocarbons, that is, fullerenes (C60, C70, C84, and C120), polyarenes (tetracene, pentacene, perylene, coronene, and hexabenzocoronene), and carbon nanotubes (single-walled and multi-walled CNTs), in water through manual grinding with V-shaped polyaromatic amphiphiles. The obtained aqueous nanocomposites are composed of nanocarbons encircled by the polyaromatic frameworks of the amphiphiles through multiple aromatic-aromatic interactions. Notably, the encapsulated photosensitive nanocarbons, such as tetracene, pentacene, and fullerene dimer, exhibit unusual stability toward UV/Vis light. [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-molecule conductance of MMM (metal–molecule-metal) junctions consisting of mono- and oligo-nuclear trans -Ru(phosphine) 4 -acetylide linkages has been summarized and compared with relevant organic junctions. • Single-molecule conductance mainly obtained by the STM-BJ (break junction) technique has been interpreted in terms of DFT and DFT-NEGF (non-equilibrium Green function) calculations, which have revealed that energy alignment between the molecules and electrodes is the key for higher conductance. • By tuning the components of the organoruthenium junctions long range carrier transport up to ∼ 4 nm with 10−2 G 0 level conductance has been achieved. MMM (metal–molecule-metal) junction exhibiting wire-like functions is an essential component of molecular circuit/electronics. Herein reviewed are recent advances in the study of single molecule conductance behavior of MMM junctions based on carbon-rich organometallics, with a particular focus on the mono- and oligo-nuclear, linear trans -Ru(phosphine) 4 -acetylide linkages. The conductance of MMM junctions determined by the STM-BJ (scanning tunneling microscopy-break junction) method has drastically improved by energy alignment between the wire part and the electrodes by tuning the components of the organometallic wire part (e.g. metal, ligand, organic linker, and anchor). The efficient energy alignment of carbon-rich organometallic systems arises from (i) the contribution of the metal d-electrons being higher in energy than the 2 s- and 2p-electrons used for purely organic junctions and much closer to the d -electron levels of metal electrodes and (ii) covalent interactions not only between anchor and electrode but also between metal and organic linker. As a result, the excellent long range carrier transport up to ∼ 4 nm with 10−2 G 0 level conductance has been achieved. Conductance behavior of MMM junctions has been successfully interpreted in terms of transmission spectra obtained by the hybrid DFT-NEGF (non-equilibrium Green function) calculations. [ABSTRACT FROM AUTHOR]

The principles and utility of photoredox catalysis in organic synthesis are described. After a brief description of the features of the two types of catalytic photoredox processes following the reductive quenching cycle (RQC) and the oxidative quenching cycle (OQC), the discussion is focused on organic transformations based on OQC, in particular the trifluoromethylation of olefinic substrates with electrophilic trifluoromethylating reagents furnishing solvolytic addition products and substitution products. It is concluded that catalytic photoredox systems are green from the point of view of harmfulness, safety, and energy source (visible light, including sunlight). Future prospects of photoredox catalysis will be also discussed. [ABSTRACT FROM AUTHOR]

For the past few years, transition-metal-catalyzed trifluoromethylation of olefins has been rapidly developing and has provided various types of organofluorine compounds containing a C(sp 3 ) CF 3 bond. In this review, we will concisely summarize recent development of trifluoromethylation of C C bonds effected by a combination of transition metal catalysis and electrophilic trifluoromethylating reagents, such as Umemoto's and Togni's reagents. [ABSTRACT FROM AUTHOR]

The trifluoromethyl group widely prevails in pharmaceutical and agrochemical compounds, while accompanying by the development of new methodologies for trifluoromethylation. Recently, the radical trifluoromethylation by photoredox catalysis has emerged. This Article describes several pioneering works and their representative mechanisms via generation of the trifluoromethyl radical based on photoredox processes. [ABSTRACT FROM AUTHOR]

An M2L4 coordination capsule or an M2L2 coordination tube was selectively formed by the combination of HgII hinges and bent bispyridine ligands. The two structures reversibly interconvert at room temperature in response to modulation of the metal-to-ligand ratio and exhibit different host-guest interaction behavior. The capsule alone encapsulates large spherical molecules, fullerenes C60 and C70, and the bound guests are released upon capsule-to-tube transformation by the simple addition of metal ions. [ABSTRACT FROM AUTHOR]

An M2L4 coordination capsule or an M2L2 coordination tube was selectively formed by the combination of HgII hinges and bent bispyridine ligands. The two structures reversibly interconvert at room temperature in response to modulation of the metal-to-ligand ratio and exhibit different host-guest interaction behavior. The capsule alone encapsulates large spherical molecules, fullerenes C60 and C70, and the bound guests are released upon capsule-to-tube transformation by the simple addition of metal ions. [ABSTRACT FROM AUTHOR]

A novel M2L2 molecular tube capable of binding fullerene C60 was synthesized from bispyridine ligands with embedded anthracene panels and Ag(I) hinges. Unlike previous molecular cages and capsules, this open-ended tubular host can accommodate a single molecule of various C60 derivatives with large substituents. The fullerene guest can then be released by using the ideal, noninvasive external stimulus, light. [ABSTRACT FROM AUTHOR]

Abstract: Visible-light promoted molecular transformations catalyzed by bimetallic species containing a [Ru(bipy)3]2+ (TB)-like fragment as the photosensitizing unit are reviewed. Catalytic reactions are classified according to the following two criteria: (1) electron transfer ( A )/energy transfer ( B ) from TB and (2) intra- (I) and inter-molecular catalyst systems (II). Reactions promoted by electron transfer ( A ) involve reductive processes such as H+-reduction giving H2 and CO2-reduction giving CO, which have been extensively studied also by using mononuclear catalysts. The catalytic H+- and CO2-reductions have been considerably improved by the use of II- A - and I- A -type bimetallic catalysts, respectively. Furthermore, as recently reported by our research group, photocatalysis is extended to organic transformations, which have been much less explored compared to transformations of small inorganic molecules mentioned above. While Sonogashira coupling is mediated by II- A -type catalysts, up-hill trans-to-cis isomerization of cyanostilbene and dimerization of α-methylstyrene follow the energy transfer processes ( B ). Thus new aspects of the photochemical bimetallic catalysis have been unveiled as mentioned above but catalyst design is still in its infancy. Continued accumulation of reaction data and mechanism analysis will lead to development of practical bimetallic photocatalysts, which promote unique reactions including up-hill reactions. [Copyright &y& Elsevier]

Our studies on polynuclear complexes containing a one-dimensional carbon chain derived from polyynyl [Fp*&z.sbnd;(C&z.tbnd6;C)n&z.sbnd;H 1n] and polyynediyl complexes [Fp*&z.sbnd;(C&z.tbnd6;C)n&z.sbnd;Fp* 2n; Fp*=FeCp*(CO)2] are reviewed. Reaction of 1n and 2n with di- and trinuclear metal carbonyl species produces polycarbon–polymetal systems with a variety of coordination structures including η2-alkyne, μ-acetylide, μ-cumulenylidene, μ3-alkylidyne and μ3-propargylidene structures. In addition to the cluster formation reactions as usually observed for acetylide and alkyne cluster compounds, the unique cluster transformations such as valence isomerization of the conjugated carbon chain, metal migration along the carbon rod and C&z.tbnd6;C cleavage reaction are observed. These transformations are realized by the flexible electronic structure of the π-conjugated carbon chain (polyynyl↔cumulenic), which fits the electronic structure of the attached metal fragments. [Copyright &y& Elsevier]

Reports on the synthesis and characterization of rare examples of mononuclear neutral hydroxoruthenium complexes and elucidates the mechanism of their dehydrative condensation reactions. Synthesis of hydroxo complexes; Condensation with protic substrates.

Reports on the preparation of mono- and dinuclear hydroxopalladium complexes (kappa2-TpiPr2,X)(py)Pd-OH (1; X = H,Br) and (mu-OH)2(Pd(kappa2-TpiPr2)(H2O))2 by base hydrolysis of the corresponding chloride complexes. Effect of dehydrative condensation with protic substrates on the functionalization of the OH part in 1.

Controlling radical localization/delocalization is important for functional materials. The present paper describes synthesis and results of electrochemical, spectroscopic, and theoretical studies of diruthenium (p‐diethynylacene)diyl complexes, Me3Si‐(C≡C)2‐Ru(dppe)2‐C≡C−Ar‐C≡C−Ru(dppe)2‐(C≡C)2‐SiMe3 (1–6) (dppe: 1,2‐bis(diphenylphosphino)ethane), and their monocationic radical species ([1]+–[6]+). The HOMO‐LUMO energy gaps can be finely tuned by the acene rings in the bridging ligands installed, as indicated by the absorption maxima of the electronic spectra of 1–6 ranging from the UV region even to the NIR region. The cationic species [1]+–[6]+ show two characteristic NIR bands, which are ascribed to the charge resonance (CR) and π‐π* transition bands, as revealed by spectroelectrochemistry. Expansion of the acene rings in [1]+–[6]+ causes (1) blue shifts of the CR bands and red shifts of the π‐π* transition bands and (2) charge localization on the acene parts as evidenced by the ESR, DFT and TD‐DFT analyses. Notably, the monocationic complexes of the larger acene derivatives are characterized as the non‐classical acene‐localized radicals. [ABSTRACT FROM AUTHOR]

Highlights a study which investigated the synthesis and structure determination of various ruthenium-aqua complexes, derived from the protonation of the ruthenium pentahydride complex TpiPrRuH5. Information on transition metal aqua complexes; Ligand substitution reaction of a labile cationic aqua complex; Discussion on the results of the study.

Herein, we report the synthesis and electrochemical and photophysical properties of aromatic hydrocarbons having one or two dimesitylborylethynyl peripherals. The mono‐ (1) and diboryl compounds (2), readily prepared by nucleophilic substitution reaction, are fairly stable to air and moisture in the solid state. The inserted ethynediyl (C≡C) spacer cancels the steric hindrance between the bulky dimesitylboryl groups and aromatic rings, leading to effective π conjugation over the B−C≡C−Ar linkages, as revealed by cyclic voltammetry. Despite the small structural differences, the photophysical properties of the benzene, naphthalene, and anthracene derivatives are different. Virtually no emission was observed from the benzene derivatives, whereas the anthracene derivatives emitted with high quantum yields both in solution and in the solid state. Notably, the naphthalene derivatives showed aggregation‐induced emission behavior. Unlike the common sterically congested triarylborane derivatives reported so far, the anthracene derivatives showed π–π*‐type absorption and emission bands, which derive from efficient intramolecular orbital interactions between the boron centers and anthracene moieties, as supported by DFT calculations. As a result, the dimesitylborylethynyl substituents effectively lower the LUMO levels of the aromatic hydrocarbon parts, whereas the HOMO levels are almost unaffected, thereby leading to materials with controllable HOMO–LUMO gaps. [ABSTRACT FROM AUTHOR]

Review: [18 refs. [ABSTRACT FROM AUTHOR]

A gemini‐type amphiphilic molecule, constituted of two V‐shaped polyaromatic amphiphiles linked by a linear acetylene spacer, was synthesized. The gemini amphiphile assembles into a well‐defined aromatic micelle (ca. 2 nm in core diameter), providing higher stability in water even at low concentration (0.09 mm) and high temperature (>130 °C). Unlike common gemini amphiphiles with aliphatic chains, the present amphiphile and its micellar assembly emit green and orange fluorescence (ΦF=33 and 9 %), respectively. Despite strong and multiple π‐stacks of the polyaromatic panels of the amphiphiles, the water‐soluble gemini aromatic micelle incorporates medium‐size to large hydrophobic compounds into the frameworks. Interestingly, the guest binding capability toward large planar molecules was enhanced by more than two times through the pre‐encapsulation of spherical molecules in the cavity. [ABSTRACT FROM AUTHOR]

A gemini‐type amphiphilic molecule, constituted of two V‐shaped polyaromatic amphiphiles linked by a linear acetylene spacer, was synthesized. The gemini amphiphile assembles into a well‐defined aromatic micelle (ca. 2 nm in core diameter), providing higher stability in water even at low concentration (0.09 mm) and high temperature (>130 °C). Unlike common gemini amphiphiles with aliphatic chains, the present amphiphile and its micellar assembly emit green and orange fluorescence (ΦF=33 and 9 %), respectively. Despite strong and multiple π‐stacks of the polyaromatic panels of the amphiphiles, the water‐soluble gemini aromatic micelle incorporates medium‐size to large hydrophobic compounds into the frameworks. Interestingly, the guest binding capability toward large planar molecules was enhanced by more than two times through the pre‐encapsulation of spherical molecules in the cavity. [ABSTRACT FROM AUTHOR]

Review: 101 refs. [ABSTRACT FROM AUTHOR]

A new protocol for solubilizing various nanocarbons such as spherical fullerenes Cn (e.g., n=60, 70, and 84), planar polyarenes (e.g., tetracene, coronene, and hexabenzocoronene), and cylindrical carbon nanotubes (e.g., SWCNTs and MWCNTs) in water through manual grinding with V ‐ shaped polyaromatic amphiphiles is described in the Full Paper by K. Kondo and M. Yoshizawa et al. on page 12741 ff. The obtained aqueous nanocomposites are composed of nanocarbons encircled by the polyaromatic panels of the amphiphiles through multiple aromatic – aromatic interactions. Notably, the encapsulated photosensitive nanocarbons, such as tetracene and fullerene dimer C120 , exhibit high stability toward light. [ABSTRACT FROM AUTHOR]

Abstract: Biologically relevant hydrophilic molecules rarely interact with hydrophobic compounds and surfaces in water owing to effective hydration. Nevertheless, herein we report that the hydrophobic cavity of a polyaromatic capsule, formed through coordination‐driven self‐assembly, can encapsulate hydrophilic oligo(lactic acid)s in water with relatively high binding constants (up to Ka=3×105  m−1). X‐ray crystallographic and ITC analyses revealed that the unusual host–guest behavior is caused by enthalpic stabilization through multiple CH–π and hydrogen‐bonding interactions. The polyaromatic cavity stabilizes hydrolyzable cyclic di(lactic acid) and captures tetra(lactic acid) preferentially from a mixture of oligo(lactic acid)s even in water. [ABSTRACT FROM AUTHOR]

Abstract: Biologically relevant hydrophilic molecules rarely interact with hydrophobic compounds and surfaces in water owing to effective hydration. Nevertheless, herein we report that the hydrophobic cavity of a polyaromatic capsule, formed through coordination‐driven self‐assembly, can encapsulate hydrophilic oligo(lactic acid)s in water with relatively high binding constants (up to Ka=3×105  m−1). X‐ray crystallographic and ITC analyses revealed that the unusual host–guest behavior is caused by enthalpic stabilization through multiple CH–π and hydrogen‐bonding interactions. The polyaromatic cavity stabilizes hydrolyzable cyclic di(lactic acid) and captures tetra(lactic acid) preferentially from a mixture of oligo(lactic acid)s even in water. [ABSTRACT FROM AUTHOR]

Eu(iii)-complexes emit highly pure and intense red luminescence in aprotic organic solvents, yet the emission is usually quenched completely in the presence of aqueous solvents. Here we report that typical Eu(iii)-complexes are readily encapsulated in the hydrophobic cavities of aromatic micelles, composed of amphiphilic molecules with bent aromatic frameworks. Whereas the emissivity of the Eu(iii)-complexes themselves is zero in aqueous solutions, the resultant host–guest nanocomposites exhibit relatively strong red emission (up to Φ = 48%) with long emission lifetimes (up to τ = 1.05 ms) even in water. Thus, encapsulation-induced emission enhancement (EIEE) of the otherwise water-deactivated luminescent compounds is demonstrated by the aromatic micelle. [ABSTRACT FROM AUTHOR]

Bulk molybdenum disulfide (MoS2) itself is virtually insoluble in common organic solvents because of the tight stacks of multiple MoS2 nanosheets. Here we report that V-shaped polyaromatic compounds with non-ionic side chains can efficiently exfoliate and disperse the inorganic nanosheets. Simple grinding and sonication (less than total 1 h) of MoS2 powder with the V-shaped compounds gave rise to large MoS2 nanosheets highly dispersed in NMP through efficient host-guest S-π interactions. DLS and AFM analyses revealed that the lateral sizes (ca. 150-270 nm) and thicknesses (ca. 2-8 nm) of the products depend on the identity of the non-ionic side chains on the V-shaped dispersant. [ABSTRACT FROM AUTHOR]

In spite of wide-ranging previous studies on synthetic macrocycles, the installation of open-close functions into the frameworks remains a challenge. We present a new polyaromatic macrocycle capable of switching between open and closed forms in response to external stimuli, namely, base and acid. The macrocycle, which is prepared in three steps, has a well-defined hydrophobic cavity with a length of around 1 nm, surrounded by four pH-responsive acridinium panels. The open and closed structures were confirmed by single-crystal X-ray analysis. The cylindrical cavity can bind long hydrophilic molecules up to 2.7 nm in length in neutral water and then release the bound guests through a reversible open-to-closed structural change upon simple addition of base. [ABSTRACT FROM AUTHOR]

In spite of wide-ranging previous studies on synthetic macrocycles, the installation of open-close functions into the frameworks remains a challenge. We present a new polyaromatic macrocycle capable of switching between open and closed forms in response to external stimuli, namely, base and acid. The macrocycle, which is prepared in three steps, has a well-defined hydrophobic cavity with a length of around 1 nm, surrounded by four pH-responsive acridinium panels. The open and closed structures were confirmed by single-crystal X-ray analysis. The cylindrical cavity can bind long hydrophilic molecules up to 2.7 nm in length in neutral water and then release the bound guests through a reversible open-to-closed structural change upon simple addition of base. [ABSTRACT FROM AUTHOR]

Review: 65 refs. [ABSTRACT FROM AUTHOR]

Review: <100 refs. [ABSTRACT FROM AUTHOR]

The ester group is one of the most ubiquitous functional groups in natural products and synthetic organic molecules. Herein, we describe the photocatalytic generation of alkyl radicals from readily accessible alkyl benzoate esters. The excited organic photocatalyst 1,4‐bis(diphenylamino)benzene (BDB) plays a vital role as a one‐electron injector. The present photoredox‐catalytic system realizes the hydroxy‐1,1‐dialkylfluoroethylation of aromatic alkenes. Finally, a strategy is developed for generation of fluoroalkyl radicals from the corresponding readily available 2‐fluorinated 1,1‐dialkylethanols. [ABSTRACT FROM AUTHOR]

We have developed novel oxytrifluoromethylation of aryl-substituted allenes by photoredox catalysis. The present photocatalytic system allows direct and stereoselective synthesis of 2-CF3-allyl acetates bearing tetrasubstituted CF3-alkene scaffolds in a single operation. The obtained CF3-allyl acetates can be applied to further functionalization as CF3-containing building blocks. [ABSTRACT FROM AUTHOR]

Recent developments of single-molecule conductance measurements allow us to understand fundamental conducting properties of molecular wires. While a wide variety of organic molecular wires have been studied so far, inorganic and organometallic molecular wires have received much less attention. However, molecular wires with transition-metal atoms show interesting features and functions distinct from those of organic wires. These properties originate mainly from metal-ligand dπ-pπ interactions and metal-metal d-d interactions. Thanks to the rich combination of metal atoms and supporting ligands, frontier orbital energies of the molecular wires can be finely tuned to lead to highly conducting molecular wires. Moreover, the unique electronic structures of metal complexes are susceptible to subtle environmental changes, leading to potential functional molecular devices. This article reviews recent advances in the single-molecule conductance study of inorganic and organometallic molecular wires. [ABSTRACT FROM AUTHOR]

By the covalent linkage of two bent bisanthracene amphiphiles with a biphenyl spacer bearing hydrophilic pendants, we synthesized a new molecular clip with a C-shaped conformation. The molecular clip provides an acyclic, open cavity surrounded by four anthracene panels in water. In contrast to previous clip- and tweezers-like compounds as well as cage-shaped compounds, the C-shaped polyaromatic cavity displays unusual wide-ranging capturing abilities toward not only planar perylene-based pigments and cylindrical single-walled carbon nanotubes but also highly branched macromolecules (carbazole dendrimers). [ABSTRACT FROM AUTHOR]

By the covalent linkage of two bent bisanthracene amphiphiles with a biphenyl spacer bearing hydrophilic pendants, we synthesized a new molecular clip with a C-shaped conformation. The molecular clip provides an acyclic, open cavity surrounded by four anthracene panels in water. In contrast to previous clip- and tweezers-like compounds as well as cage-shaped compounds, the C-shaped polyaromatic cavity displays unusual wide-ranging capturing abilities toward not only planar perylene-based pigments and cylindrical single-walled carbon nanotubes but also highly branched macromolecules (carbazole dendrimers). [ABSTRACT FROM AUTHOR]

Unlike common polyaromatic hydrocarbons, acridine is a characteristic compound bearing both π-stackable large surfaces and a protonable nitrogen atom. Here we report the first synthesis of a supramolecular capsule with multiple acridine panels. In water, the assembly and disassembly of the capsule reversibly occur under neutral and acidic conditions, respectively (≥10 cycles). Notably, the pH-responsive capsule encapsulates a variety of large hydrophobic compounds (up to 1.6 nm in diameter) such as coumarins, metallophthalocyanines and subphthalocyanine in neutral water and subsequently releases them by simple addition of acid. [ABSTRACT FROM AUTHOR]

For the development of novel nanospace with unique electrostatic character, we prepared new capsular and tubular nanostructures by the quantitative assembly of metal ions and bent bisacridinium ligands. The capsule and tube have closed spherical and open cylindrical cavities, respectively, with diameters of around 1 nm surrounded by cationic polyaromatic panels. Thanks to the facile synthetic protocol (three steps), another polycationic capsule with an elliptical nanocavity was also prepared by using an elongated ligand. In spite of the absence of pendant hydrophilic groups, the spherical polyaromatic capsule shows sufficient water solubility due to the polycationic shell. Moreover, the highly cationic cavity (12+) can selectively encapsulate anionic organic compounds in water. [ABSTRACT FROM AUTHOR]

We have developed a new strategy for catalytic aminohydroxylation of olefins with an N -protected iminopyridinium ylide as the amine source. Iminopyridinium ylides N -protected with TFAc (trifluoroacetyl), Boc ( tert -butoxycarbonyl), Troc (2,2,2-trichloroethoxycarbonyl), and Alloc (allyloxycarbonyl) groups serve as N -centered radical precursors when combined with fac -[Ir(ppy) 3 ] photocatalysis and Sc(OTf) 3 catalysis. The dual Ir photoredox/Sc(OTf) 3 catalysis proves to be effective for aminohydroxylation of olefins under mild reaction conditions to provide 2-aminoalcohol derivatives bearing a primary amino group. [ABSTRACT FROM AUTHOR]

In the realm of metallaphotocatalytic C−H activation strategy, the direct excitation of the transition metal which plays the dual role of light energy harnessing alongside performing the bond breaking and forming is a rare phenomenon. In this context we have developed the first photo‐induced Rh‐catalyzed ortho‐alkynylation under ambient conditions without the requirement of silver salt, photocatalyst (PC) or any engineered substrate or catalyst. The transformation functions by the specific cooperative effect of a six‐membered rhodacycle which is the photo‐responsive species. The catalytic system allows the conjugation of arenes with sp3‐rich pharmacophoric fragments. The control experiments as well as the computational studies resolve the mechanistic intricacies for this transformation. An outer sphere electron transfer process from Rh to alkynyl radical is operative for the present photo‐induced transformation over the more common oxidative addition or 1,2‐migratory insertion pathways. [ABSTRACT FROM AUTHOR]

In the realm of metallaphotocatalytic C−H activation strategy, the direct excitation of the transition metal which plays the dual role of light energy harnessing alongside performing the bond breaking and forming is a rare phenomenon. In this context we have developed the first photo‐induced Rh‐catalyzed ortho‐alkynylation under ambient conditions without the requirement of silver salt, photocatalyst (PC) or any engineered substrate or catalyst. The transformation functions by the specific cooperative effect of a six‐membered rhodacycle which is the photo‐responsive species. The catalytic system allows the conjugation of arenes with sp3‐rich pharmacophoric fragments. The control experiments as well as the computational studies resolve the mechanistic intricacies for this transformation. An outer sphere electron transfer process from Rh to alkynyl radical is operative for the present photo‐induced transformation over the more common oxidative addition or 1,2‐migratory insertion pathways. [ABSTRACT FROM AUTHOR]

Epoxidation of styrenes is efficiently catalyzed by micelle-like molecular capsules providing Mnporphyrins in water at room temperature. In contrast to usual Mn-porphyrin catalysts, the encapsulated Mnporphyrin catalysts show higher reactivities (up to 1350 TON for 1 h) even without the addition of imidazole ligands. Spectroscopic studies and competitive-binding experiments demonstrate that the efficient catalytic cycle stems from the enforced proximity of the catalyst and substrates as well as the smooth replacement of the products by substrates in the hydrophobic cavity of the capsule. [ABSTRACT FROM AUTHOR]

A regio- and stereoselective synthesis of trifluoromethylated alkenes bearing four different substituents has been developed. Stereocontrolled sulfonyloxytrifluoromethylation of unsymmetric internal alkynes with an electrophilic CF3 reagent, namely the triflate salt of the Yagupol'skii-Umemoto reagent, in the presence of an Ir photoredox catalyst under visible-light irradiation afforded trifluoromethylalkenyl triflates with well-predictable stereochemistry resulting from anti addition of the trifluoromethyl and triflate groups. Subsequent palladium-catalyzed cross-couplings led to tetrasubstituted trifluoromethylated alkenes in a highly stereoselective manner. The present method is the first example of a facile one-pot synthesis of tetrasubstituted trifluoromethylated alkenes from simple alkynes. [ABSTRACT FROM AUTHOR]

A regio- and stereoselective synthesis of trifluoromethylated alkenes bearing four different substituents has been developed. Stereocontrolled sulfonyloxytrifluoromethylation of unsymmetric internal alkynes with an electrophilic CF3 reagent, namely the triflate salt of the Yagupol'skii-Umemoto reagent, in the presence of an Ir photoredox catalyst under visible-light irradiation afforded trifluoromethylalkenyl triflates with well-predictable stereochemistry resulting from anti addition of the trifluoromethyl and triflate groups. Subsequent palladium-catalyzed cross-couplings led to tetrasubstituted trifluoromethylated alkenes in a highly stereoselective manner. The present method is the first example of a facile one-pot synthesis of tetrasubstituted trifluoromethylated alkenes from simple alkynes. [ABSTRACT FROM AUTHOR]

A simple and regiospecific aminohydroxylation of olefins by photoredox catalysis has been developed. N-protected 1-aminopyridinium salts are the key compounds and serve as amidyl radical precursors by the action of Ir photocatalysts, fac-[Ir(ppy)3] and [Ir(ppy)2(dtbbpy)](PF6) (ppy=2-pyridylphenyl, dtbbpy=4,4′-di- tert-butyl-2,2′-bipyridine). The present photocatalytic system allows for synthesis of vicinal aminoalcohol derivatives from olefins with various functional groups under mild reaction conditions with easy handling. [ABSTRACT FROM AUTHOR]

Host–guest assemblies of a designed 1,4-bis(diarylamino)naphthalene and V-shaped aromatic amphiphiles consisting of two pentamethylbenzene moieties bridged by an m -phenylene unit bearing two hydrophilic side chains emerged as highly reducing photoredox catalysis systems in water. An efficient demethoxylative hydrogen transfer of Weinreb amides has been developed. The present supramolecular strategy permits facile tuning of visible-light photoredox catalysis in water. [ABSTRACT FROM AUTHOR]