Loredana Valenzano

BODIPY-based ratiometric fluorescent probes for the sensitive and selective sensing of cyanide ions

Three BODIPY-based ratiometric fluorescent probes (1, 2 and 3), with two being highly soluble in aqueous solution, were prepared by the condensation of 2-formyl-BODIPY dyes with 2,3,3-trimethyl-1-propyl-3H-indolium iodide and 2,3,3-trimethyl-1-(3-sulfonatepropyl)-3H-indolium for the selective and sensitive ratiometric fluorescent responses to cyanide ions.

Functionalization of BODIPY dyes at 2,6-positions through formyl groups

A 2,6-diformyl-BODIPY dye has been modified by transforming its formyl groups at the 2,6-positions into different functional groups such as hydroxyl, carboxylic acid, cyano, nitro and oxime groups, resulting in a series of new BODIPY dyes. The optical properties of the resulting BODIPY dyes significantly depend on the functional groups at the 2,6-positions.

γ Phase RDX: Initial study of geometry, spectrum and EOS

We present a full 3D periodic density functional theory study of the geometry and vibrational spectrum of γ phase nitramine, hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The B3LYP-D* functional as adjusted for molecular solids from Grimmes semi-empirical approach for molecules is used to better describe the van der Waals interactions in this system. Specifically, the low terahertz portion of the spectrum is computed to determine modes that change substantially in behavior with respect to an alpha phase that is near the transition pressure for the system. These key modes provide possible clues into the nature of the α .γ phase transformation.

Quantum chemistry as a tool to assess energetic and spectroscopic properties of C1 and C2 hydrocarbons in MOF-74-Mg

Periodic boundary conditions as implemented within a linear combination of atomic orbital approach are applied to determine the infrared spectra of methane, acetylene, ethylene, and ethane in MOF-74-Mg. Intensities and frequency shifts with respect to the molecules in the gas phase are described and discussed with respect to geometrical arrangements and structural modifications of the molecules adsorbed in the framework. Given the predictive nature of the work and in the attempt of providing a better ground for comparison with experimental spectroscopic observations, different molecular loadings are considered where one (low loading), three (medium loading), and six (full loading) molecules are adsorbed at the primary adsorption binding site identified by the MgO5 inorganic brick of the MOF structure. In addition, enthalpies of adsorption are reported for methane and acetylene whose addition to previous works by the same authors, provides an overall assessment at electronic structure level of the energetic behavior of C1–C4 hydrocarbons in MOF-74-Mg. Calculations are conducted at B3LYP-D2* level of theory as implemented in the Crystal14 program.

Calculation of the vibrational spectra of α-rdx using the grimme DFT potential

The density-functional theory (DFT) potential by Grimme has been proposed for describing longrange dispersion corrections. This potential has been implemented into the CRYSTAL09 program and used to calculate the vibrational spectra in α-RDX at equilibrium. The frequencies and intensities are reported and compared with prior theory and experiment where possible.

The terahertz infrared spectrum of cyclotrimethylenetrinitramine: Targeting anharmonic modes for the fingerprinting and detection of RDX

Recent approaches to the modeling of molecular solids have provided for a dramatic improvement in the prediction of zero Kelvin behavior for some properties of interest. Most notably the vibrational spectrum for these systems can now be calculated robustly via ab initio methods employing density functional theory. This improvement, however, leads to a quandary: the accurate physical modeling of these systems at zero Kelvin in many cases will not provide values and even physical behavior matching experimental values under ambient conditions. We examine this quandary in detail by considering zero Kelvin calculations using the B3LYP-D* functional of the terahertz infrared spectrum of the energetic material cyclotrimethylenetrinitramine (RDX). Most importantly we show what knowing the deviation from the simple harmonic approximation of a given mode at zero Kelvin says about the anharmonicity of the mode near ambient volumes. Finally, we discuss the practical implications for using ab initio calculations to cr...