Light is an exceptional external stimulus for establishing precise control over the properties and functions of chemical biological systems, which enabled through use molecular photoswitches. Ideal photoswitches are operated with visible light only, show large separation absorption bands functional in various solvents including water, posing unmet challenge. Here we a class fully-visible-light-operated photoswitches, Iminothioindoxyls (ITIs) that meet these requirements. ITIs band 100 nm,...

Pressure-induced polymerization of aromatic compounds leads to novel materials containing sp3 carbon-bonded networks. The choice the molecular species and control their arrangement in crystal structures via intermolecular interactions, such as arene-perfluoroarene interaction, can enable design target polymers. We have investigated structure compression pressure-induced reaction kinetics two polycyclic 1:1 cocrystals, naphthalene/octafluoronaphthalene (NOFN) anthracene/octafluoronaphthalene...

Liquid water has a primary role in ruling life on Earth wide temperature and pressure range as well plethora of chemical, physical, geological, environmental processes. Nevertheless, full understanding its dynamical structural properties is still lacking. Water molecules are associated through hydrogen bonds, with the resulting extended network characterized by local tetrahedral arrangement. Two different structures liquid, called low-density (LDW) high-density (HDW) water, have been...

The synthesis of hydrogenated carbon nanothreads at tens GPa from aromatic systems is one the most brilliant recent findings in high-pressure science. C-nanothreads combine high tensile strength diamond with flexibility polymers, and many efforts are currently being undertaken to taylor some useful physicochemical properties by smartly modifying their local structure. We present double core diamond-like two cores bound a conjugated C, polyacetylene-like backbone. also form protecting sheath...

This study addresses azobenzene's structural compression and reactivity under hydrostatic high-pressure conditions. Synchrotron X-ray diffraction data of single crystals compressed with neon as the pressure-transmitting medium allowed refinement of...

Synthesis of carbon nanothreads from pyridine under variable high-pressure and high-temperature conditions discloses the role H-bonding in kinetic control reaction.

In this work we have performed an extensive high pressure study of the condensed phases pyridine by Raman and IR spectroscopy. We evidenced three different polymorphs, two crystalline, one glassy established conditions in which they exist as stable or metastable several compression/decompression experiments both on annealed not samples. Crystallization phase transitions are found to be kinetically driven. The vibrational spectra extremely complex due low symmetry crystals, implies a large...

Angle-dispersive X-ray diffraction and Fourier transform infrared spectroscopy have been employed to study the phase diagram of urea crystal beyond 15 GPa at temperatures in excess 400 K. Previously reported Bridgman II was structurally characterized for first time, it is discovered that coincides with room-temperature IV. Large metastability P–T regions were identified all phases sequence I–III–IV–V, ascribed difficulty disrupt H-bonding network, a prerequisite accomplish molecular...

One-step high-pressure synthesis of 2D crystalline double nanothreads linked by azo groups.

Until recently, saturated carbon nanothreads were the missing tile in world of low-dimension nanomaterials. These one-dimensional fully polymers possess superior mechanical properties by combining high tensile strength with flexibility and resilience. They can be obtained compressing aromatic heteroaromatic crystals above 15 GPa exploiting anisotropic stress that achieved diamond anvil cell technique. Recently, double-core synthesized azobenzene crystals, achieving remarkable result...

Picene is a polycyclic aromatic hydrocarbon belonging to the class of phenacenes which have been recently found behave as high-temperature superconductors upon alkali metal doping. The electronic properties organic crystals can be finely and largely modified by density changes obtained application an external pressure. In this work, role pressure in tuning optical crystalline picene has investigated from room conditions up 15 GPa through measurement UV–visible absorption spectra, two-photon...

The pressure-induced transformation of molecular crystals can give rise to new materials characterized by intriguing hardness or energetic properties. Mechanisms regulating these reactions at the level result from a complex interplay among crystal structure, lattice dynamics, and electronic Here, we show that formation three-dimensional amorphous carbon nitride compressing phase II s-triazine is controlled competition between two different mechanisms, one entirely structural other...

Pressure is an extraordinary tool to modify direction and strength of intermolecular interactions with important consequences on the chemical stability molecular materials. The decrease distance among nearest neighbour molecules can give rise reactive configurations reflecting crystal arrangement leading association processes. In this context, role H-bonds very peculiar because their usual strengthening rising pressure does not necessarily configure a reaction activation energy but,...

Saturated carbon nanothreads are one of the most attractive new materials produced under high pressure in last years. Nanothreads can be considered as a monodimensional diamond; fact, they preserve some mechanical properties diamond itself, like stiffness, but their intrinsic flexibility makes them excellent nanowires. Since discovery, many advancements have been made, and nowadays, obtained from compression several aromatic molecular crystals. However, it is often not clear why certain...

Two-photon excitation profiles and fluorescence spectra have been measured as a function of pressure in diamond anvil cell up to 15.5 GPa crystal phases I II the glassy form pyridine. The emission intensity increases by about 6 orders magnitude going from liquid crystalline at 3 further with pressure. This is explained an energy inversion lowest (1)B(1) (nπ*) (1)B(2) (ππ*) excited states likely due involvement lone pair N atom intermolecular CH···N bonds. These interactions characterize are...

Pressure is extremely efficient to tune intermolecular interactions, allowing the study of mechanisms regulating, at molecular level, structure and dynamics condensed phases. Among simplest molecules, water represents in many respects a mystery despite its primary role ruling most biological, physical, chemical processes occurring nature. Here we report careful characterization dynamic regime change associated with low-density high-density forms liquid by measuring line shape OD stretching...

Clarifying the structure/dynamics relation of water hydrogen-bond network has been aim extensive research over many decades. By joining anvil cell high-pressure technology, femtosecond 2D infrared spectroscopy, and molecular dynamics simulations, we studied, for first time, spectral diffusion stretching frequency an HOD impurity in liquid as a function pressure. Our experimental simulation results concordantly demonstrate that rate is almost insensitive to applied This behavior contrast with...

The optical properties of picene at ambient conditions have been investigated through the measurement UV/Vis absorption and fluorescence spectra excitation profiles, using one- two-photon excitation, in solution crystal phase. For solvated an assignment vibronic structure transitions to four lowest-energy excited singlet states (S(1)-S(4)) has obtained from data, assigned. solid phase can be interpreted according single molecule analysis. Nevertheless, strong increase density spectral region...

The pressure-induced reactivity of aromatic molecules in the crystal phase has been recently demonstrated to be a practicable route for synthesis crystalline nanothreads. formation these attracting materials is ascribed stress anisotropy induced by uniaxial compression. In case aniline, attainment NH2-enriched carbon nanothreads above 30 GPa related intrinsic due presence strong directional H-bonds. Here, we have probed aniline at lower pressure and higher temperature with multifold purpose...

The high-pressure transformation of s-triazine to an extended amorphous carbon incorporating a large amount nitrogen has been studied by Fourier transform infrared spectroscopy. reaction, occurring at ambient temperature around 8 GPa, is found be extremely sensitive temperature, as the reaction onset lowered 4 GPa 530 K. Also, laser irradiation allows very selective trigger reactivity below threshold likely due population ππ* states. Independently and conditions, two different products are...

The room temperature photoinduced reactivity of liquid ethanol has been studied as a function pressure up to 1.5 GPa by means diamond anvil cell. Exploiting the dissociative character lowest electronic excited states, reached through two-photon absorption near-UV photons (350 nm), irreversible reactive processes have triggered in pure system. active species are radicals forming along two main dissociation channels involving split C−O and O−H bonds. characterization reaction products...

The room-temperature reactivity of liquid methanol induced by two-photon absorption near UV photons (350 nm) was studied as a function pressure. Different chemical reactions were triggered the radical species produced through population lowest electronic excited singlet state because its dissociative character. Experiments performed at room temperature between 0.1 and 1.8 GPa on CH3OH 0.2 1.5 CD3OH. irradiation cycles constant pressure conditions, FTIR Raman spectra measured to monitor...

Homogeneous melting of crystals is a complex multistep process involving the formation transient states at temperatures considerably higher than point. The nature and persistence these metastable structures are intimately connected to process, precise definition temporal boundaries phenomena not yet available. We set up specifically designed experiment probe by infrared absorption spectroscopy entire dynamics, ranging from tens picoseconds microseconds, superheating an ice crystal. In spite...