<Emphasis Type="Italic">Ab initio</Emphasis> study of scandium fluoride molecules: ScF,ScF<Subscript>2</Subscript>, AND ScF<Subscript>3</Subscript>

Equilibrium geometric parameters, normal mode frequencies and intensities in IR spectra, atomization enthalpy, and relative energies of low-lying electronic states of scandium fluoride molecules (ScF, ScF₂, and ScF₃) are calculated by the coupled-cluster method (CCSD(T)) in triple-, quadruple, and quintuple-zeta basis sets with the subsequent extrapolation of the calculation results to the complete basis set limit. The ScF molecule is also studied by the CCSDT technique. The error in the approximate calculation of triple excitations in the CCSD(T) method does not exceed 0.002 Å for the equilibrium internuclear distance R _e, 4 cm^?1 for the vibrational frequency, and 0.2 kcal/mol for the dissociation energy of the molecule. In the ground electronic state \(\tilde X^2 \) A ₁(C _2ν ) of ScF₂ molecules, R _e(Sc-F) = 1.827 Å and α_e(F-Sc-F) = 124.2°; the energy barrier to bending (linearization) h = E _min(D _g8h ) ? E _min(C_2ν) = 1652 cm^?1. The relative energies of Ã²Δ _g and \(\tilde B^2 \)Π _g electronic states are 3522 cm^?1 and 14633 cm^?1 respectively. The bond distance in the ScF₃ molecule (\(\tilde X^1 \) A′₁, D _3h ) is refined: R _e(Sc-F) = 1.842 Å. The atomization enthalpies Δ_at H ₂₉₈ ⁰ of ScF _k molecules are 139.9 kcal/mol, 289.0 kcal/mol, and 444.8 kcal/mol for k = 1, 2, 3 respectively.     

Photo- and thermochromic spiranes 32*. Synthesis and photochromism of 3-methyl-4-oxospiro(2,3-dihydronaphtho-[2,1-<Emphasis Type="Italic">e</Emphasis>]-1,3-oxazine-2,2'-[2H]-chromenes)

Spiropyrans of the naphthoxazinone series have been obtained containing various substituents in the [2H]-chromene portion of the molecule. The spatial structure of a spiropyran containing ortho-positioned hydroxyl and formyl groups was established by X-ray structural analysis. The photochromic properties of the obtained compounds have been studied. For Communication 31 see [1]. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 273-283, February, 2009.     

Photochromic and thermochromic spiranes 33. Synthesis of a new indolinonaphthoxazino- bisspiropyran and investigation of its photochromic characteristics

A new unsymmetrical bisspiropyran was synthesized on the basis of 2,4-dihydroxyisophthalic aldehyde with naphthoxazinone and indoline fragments in the structure. The structure of the obtained compound was proved by the data from ¹H NMR and IR spectroscopy and X-ray crystallographic analysis. The photochromic characteristics of the obtained compound were investigated. It was established by means of the data from B3LYP/6-31G** quantum-chemical calculations that irradiation of a solution of the obtained biphotochrome with unfiltered light leads to opening of both pyran fragments. This is the first corroborated example of the twofold cleavage of C_spiro–O bonds for compounds of this class.     

Synthesis and study of L-arabinopyranosides of 5- and 6-nitroindoles

Condensation of 5- or 6-nitroindoline with L-arabinose gave 1--L-arabinopyranosyl-5 (or 6)-nitroindolines, which, after acetylation, dehydrogenation, and removal of the protective groups, are converted to 1--L-arabinopyranosyl-5(or 6)-nitroindoles and then to the corresponding amino derivatives. 1--L-Arabinopyranosyl-6-nitro-3-bromo-(iodo)indoles were obtained. The selective 2-O- and 3-O-deacetylation of 1-(2, 3, 4-tri-O-acetyl)--L-arabinopyranosyl-6-nitroindole was accomplished.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 224–229, February, 1979.     

Eternal Inflation, Black Holes, and the Future of Civilizations

We discuss the large-scale structure of the universe in inflationary cosmologyand the implications that it may have for the long-term future of civilizations.Although each civilization is doomed to perish, it may be possible to transmitits accumulated knowledge to future civilizations. We consider several scenariosof this sort. If the cosmological constant is positive, it eventually dominates theuniverse and bubbles of inflationary phase begin to nucleate at a constant rate.Thermalized regions inside these inflating bubbles will give rise to new galaxiesand civilizations. It is possible in principle to send a message to one of them. Itmight even be possible to send a device whose purpose is to recreate anapproximation of the original civilization in the new region. However, the messageor device will almost certainly be intercepted by black holes, which nucleate ata much higher rate than inflating bubbles. Formation of new inflating regionscan also be triggered by gravitational collapse, but again the probability is low,and the number of attempts required for a positive outcome is enormous. Theprobability can be higher if the energy scale of inflation is closer to the Planckscale, but a high energy scale produces a tight bound on the amount of informationthat can be transmitted. One can try to avoid quantum tunneling altogether, butthis requires a violation of quantum inequalities which constrain the magnitudeof negative energy densities. However, the limits of validity of quantuminequalities are not clear, and future research may show that the required violationis in fact possible. Therein lies the hope for the future of civilizations.