Laser-Induced Selectivity for Dimerization Versus Polymerization of Butadiene Under Pressure

Citroni, Mario; Ceppatelli, Matteo; Bini, Roberto; Schettino, Vincenzo

doi:10.1126/science.1068451

Cited by 126 publications

(137 citation statements)

References 28 publications

Supporting

Mentioning

135

Contrasting

Order By: Relevance

“…Unique nano-composite materials could be synthesized in this way. A strong advantage of highpressure polymerization techniques with respect to more conventional catalytic protocols is precisely that these techniques allow the use of catalysts and radical initiators to be avoided [21][22][23] , which is indispensable to determine the intrinsic role of spatial confinement on polymerizing matter. Indeed, pressure is the most efficient tool to reduce intermolecular distances, thereby permitting continuous tuning of the corresponding interactions and allowing the chemical reactions to occur, which are in some cases enhanced by ultraviolet (UV) light irradiation, when a critical intermolecular distance is approached in this way 24 .…”

mentioning

confidence: 99%

“…To our knowledge, ethylene was never polymerized in a nano-confining host material, neither by catalytic nor by non-catalytic routes. Polymerization was induced by applying pressures of 0.5-1.5 GPa to the confined reactant and using UV irradiation (351-364 nm) as an optical catalyst, which we have already shown to be efficient conditions for polymerizing bulk ethylene and other simple hydrocarbons [21][22][23] . The composite was characterized by optical spectroscopy, and single-crystal and powder X-ray diffraction (XRD).…”

mentioning

confidence: 99%

See 1 more Smart Citation

High-pressure synthesis of a polyethylene/zeolite nano-composite material

et al. 2013

Self Cite

View full text Add to dashboard Cite

Meso/micro-porous solids, such as zeolites, are complex materials used in an impressive range of applications. Here we photo-polymerized ethylene using non-catalytic high-pressure techniques at 0.5-1.5 GPa under ultraviolet (351-364 nm) irradiation on a sub-nanometre scale in the channels of a pure SiO 2 zeolite, silicalite, to obtain a unique nano-composite material with drastically modified mechanical properties. The structure obtained contains single polyethylene chains, which adapt very well to the confining channels as shown by optical spectroscopy and X-ray diffraction. The formation of this nano-composite results in significant increases in bulk modulus and density, and the thermal expansion coefficient changes sign from negative to positive with respect to silicalite. Mechanical properties may thus be tuned by varying the amount of polymerized ethylene. Our findings could allow the high-pressure, catalyst-free synthesis of a unique generation of technological, functional materials based on simple hydrocarbons polymerized in confining meso/micro-porous solids.

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

High-pressure synthesis of a polyethylene/zeolite nano-composite material

et al. 2013

Self Cite

View full text Add to dashboard Cite

show abstract

“…It is therefore evident that these reactions become more and more relevant with increasing pressure because the increasing density of the materials results in reduced intermolecular distances that favor the interaction between excited and groundstate molecules. The efficiency of these processes is also attested to by several reactions occurring in pure condensed unsaturated hydrocarbons triggered by 2-photon (TP) excitations realized with cw (continuous wave) low-power laser sources that, because of the small cross-section of TP transitions, ensure catalytic amounts of excited species (5,6,12,15).Among simple molecular systems, water is of primary importance because of its abundance on the Earth's surface and because it is the most abundant polyatomic molecule in the visible universe (16). In addition, chemical reactions taking place in liquid water are essential for many processes in environmental science and biology.…”

mentioning

confidence: 99%

High-pressure photodissociation of water as a tool for hydrogen synthesis and fundamental chemistry

Ceppatelli¹,

Bini²,

Schettino³

2009

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

View full text Add to dashboard Cite

High-pressure methods have been demonstrated to be efficient in providing new routes for the synthesis of materials of technological interest. In several molecular compounds, the drastic pressure conditions required for spontaneous transformations have been lowered to the kilobar range by photoactivation of the reactions. At these pressures, the syntheses are accessible to large-volume applications and are of interest to bioscience, space, and environmental chemistry. Here, we show that the short-lived hydroxyl radicals, produced in the photodissociation of water molecules by near-UV radiation at room temperature and pressures of a few tenths of a gigapascal (GPa), can be successfully used to trigger chemical reactions in mixtures of water with carbon monoxide or nitrogen. The detection of molecular hydrogen among the reaction products is of particular relevance. Besides the implications in fundamental chemistry, the mild pressure and irradiation conditions, the efficiency of the process, and the nature of the reactant and product molecules suggest applications in synthesis.high-pressure chemistry ͉ photocatalysis T he application to molecular systems of suitable external pressures causes a density increase that determines a strengthening of the intermolecular interactions leading first to changes in the aggregation state of the material, and then to crystalline phase transitions (1). Upon further compression, the possible overlap of the electronic density of nearest-neighbor molecules can also trigger a complete reconstruction of the chemical bonds, giving rise to new materials in some cases recoverable at ambient conditions (2). After the pioneering work on the pressure-induced polymerization of cyanogen (3) and acetylene (4) crystals, several simple molecular crystals have been reported to react upon application of suitable external pressure, giving rise to high-quality polymeric (5-7) and amorphous (8-10) materials of potential technological interest. These transformations require pressures from several to 100 GPa, as in the nitrogen case (7), but the reaction threshold pressure has been successfully lowered in almost all of the unsaturated hydrocarbons studied so far by a photoactivation of the high-pressure reactions (11). In some cases, an increasing selectivity (5) or the opening of new reaction paths (12) is also observed. These syntheses are appealing because only physical methods are used, thus representing an interesting perspective for a green chemistry (13).The mechanisms governing the photoinduced reactivity of molecular systems derive from the structural and charge density distribution changes after an electronic transition. In general, the excited molecule is characterized by a reduced binding order that determines molecular bonds stretching, a lowering of rotational and torsional barriers, an increase in the polarity, and even dissociation and ionization. These species can be particularly aggressive from a chemical point of view and, depending on their lifetime and free mean path, can trigger a...

show abstract

“…the charge distribution within the molecule, and finally by a complete reconstruction of the bonding scheme. The latter step generally results in the formation of extended materials which can be recovered at ambient conditions, as reported for some polymers and amorphous compounds [5][6][7], revert back to the pristine substances, as observed for the simplest molecules like N 2 [8], CO 2 [9][10][11] and formic acid [12], or even partly or completely decompose into small molecules different from the starting ones, as observed in carbon monoxide [13] and nitromethane [14], respectively. Besides inducing chemical reactivity, high pressure methods are extremely powerful also to gain insight at the molecular level on the reaction mechanisms by tuning independently pressure, temperature and photoexcitation.…”

Section: Introductionmentioning

confidence: 90%

“…Final-ly, a selective electronic excitation permits the charge distribution in the molecule (for example inducing π ! π* transitions) to be modified in such a way that it can behave as a reaction initiator [5,6,16]. The latter issue is particularly interesting in view of reducing the pressure threshold for the reaction occurrence, thus making these high pressure reactions also appealing from a synthetic point of view because of a possible scale up of the process to large volume apparatuses nowadays operating on volumes of several litres and pressures up to 1 GPa.…”

Section: Introductionmentioning

confidence: 99%

Probing high-pressure reactions in heterogeneous materials by Raman spectroscopy

Ceppatelli¹,

Gorelli²,

Haines³

et al. 2014

Zeitschrift Für Kristallographie – Crystalline Materials

Self Cite

View full text Add to dashboard Cite

The characterization of pressure induced structural and chemical transformations employing the Diamond Anvil Cell (DAC) technique often requires a high spatial resolution. This is due to the small sample dimensions when the compression reaches the megabar range, or when heterogeneous materials are obtained in pressure induced chemical reactions. The characterization of these samples can be performed by using synchrotron light based techniques, which can provide optical or X-ray spots of few microns, whereas laboratory experiments are limited to Raman spectroscopy. Here we describe a cutting-edge Raman system with a transverse spatial resolution of 1-3 μm dedicated to the characterization of samples compressed in DACs. A few examples of the application of this technique to characterize different heterogeneous materials before and after high-pressure chemical reactions are reported to enlighten the performances of the system.

show abstract

Laser-Induced Selectivity for Dimerization Versus Polymerization of Butadiene Under Pressure

Cited by 126 publications

References 28 publications

High-pressure synthesis of a polyethylene/zeolite nano-composite material

High-pressure synthesis of a polyethylene/zeolite nano-composite material

High-pressure photodissociation of water as a tool for hydrogen synthesis and fundamental chemistry

Probing high-pressure reactions in heterogeneous materials by Raman spectroscopy

Contact Info

Product

Resources

About