Computational protocol: MM quadruply bonded complexes supported by vinylbenzoate ligands: synthesis, characterization, photophysical properties and application as synthons††Electronic supplementary information (ESI) available: Transient absorption plots and kinetics, time resolved IR plots, NIR emission. CCDC 1015787 and 1015788. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc02542cClick here for additional data file.Click here for additional data file.

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Protocol publication

[…] Density functional theory was used to perform electronic structure calculations on model complexes utilizing the Gaussian 09 suite of programs. The Becke three parameter correlation functional combined with the Lee, Yang, and Parr exchange functional was employed (B3LYP)., Model complexes were optimized in the gas phase to a minimum as confirmed by the lack of imaginary frequencies in a vibrational analysis. For C, H, and O the 6-31g* basis set was used. For Mo and W, the Stuttgart/Dresden energy-consistent pseudopotential (SDD) was used to represent the core orbitals and the SDD basis set. Formate was used instead of TiPB in order to simplify the calculations and save on computational resources. This substitution allows the complexes to obtain an idealized symmetry higher than that with TiPB. The complexes were idealized to the highest symmetry possible while still containing an inversion center. A correction factor of 0.96 was applied to the calculated vibrational frequencies to correlate them with experimentally observed frequencies.Visualizations of the molecular orbitals was performed with GaussView 5.0 with an isovalue of 0.02. [...] Single crystals of 1A and 2A were isolated as yellow and orange blocks, respectively, and handled under a pool of fluorinated oil. Examination of the diffraction pattern was done on a Nonius Kappa CCD diffractometer with Mo Kα radiation. All work was done at 150 K using an Oxford Cryosystems Cryostream Cooler. Data integration was done with Denzo, and scaling and merging of the data was done with Scalepack. The structures were solved by the direct methods program in SHELXS-13. Full-matrix least-squares refinements based on F2 were performed in SHELXL-13, as incorporated in the WinGX package. For each methyl group, the hydrogen atoms were added at calculated positions using a riding model with U(H) = 1.5U eq (bonded carbon atom). The rest of the hydrogen atoms were included in the model at calculated positions using a riding model with U(H) = 1.2U eq (bonded atom). Neutral atom scattering factors were used and include terms for anomalous dispersion. One isopropyl group in the TiPB moiety of 1A was disordered over two locations. This disorder was modeled using similarity restraints as well as rigid bond restraints to ensure reasonable bond lengths and anisotropic displacement parameters. The occupancy of these two parts was allowed to refine on a free variable leading to an occupancy of ∼54% in the major component.Compound 2A had disorder in the p-vinyl moiety. This disorder was handled similarly to that in 1A and the occupancy of the major component refined to be ∼50%. After final refinement of 2A several residual ‘Q’ peaks remained in the difference map and were unable to be adequately modeled as solvent. To remove this electron density the SQUEEZE protocol of the PLATON suite of programs was used to exclude 45 electrons from a void of 250 Å3. This electron density likely corresponds to disordered hexanes used in crystallization of 2A. [...] Nanosecond TA was performed on samples in 1 × 1 cm square quartz cuvettes with Kontes stopcocks. Measurements were made on a home-built instrument pumped by a frequency-doubled (532 nm) or frequency tripled (355 nm) Spectra-Physics GCR-150 Nd:YAG laser (fwhm ≈ 8 ns, ∼5 mJ per pulse). The power at the sample was set to 100 mW Signal from a Hamamatsu R928 photomultiplier tube was processed with a Tektronics 400 MHz oscilloscope (TDS 380). For 1A, 1B, 2B, and 3A the samples were excited with 355 nm and for 2A and 4A the samples were excited at 532 nm with laser power at the sample of 100 mW.Femtosecond transient absorption experiments were performed with a Ti:sapphire and regenerative amplifier combination (1 kHz, 50 fs full width at half-maximum) that has been previously described. Samples were prepared with absorbances of ∼0.3–0.8 in a 1.0 mm quartz cuvette with Kontes top. Excitation power at the sample was 1–2 μJ. Spectra collected underwent wavelength calibration and group velocity dispersion corrections.Time-resolved infrared spectroscopy experiments, previously described, were performed with a Ti:sapphire and regenerative amplifier combination (1 kHz, 50 fs fwhm). Samples of 2A, 2B and 4A were prepared with an absorbance of ∼1 at λ max in THF solution. A PerkinElmer semi-demountable cell with a 0.1 mm Teflon spacer between 4 mm CaF2 windows was used to provide an airtight sample chamber. The compounds 2A, 2B, and 4A were excited with a laser power of ∼1 μJ at 515 nm, 515 nm and 675 nm, respectively.In general, kinetics were fit to a sum of exponential decay terms, S(t) = ∑i A i exp(–1/τ i) + C, using Igor Pro 6.0 or SigmaPlot 12.0, where A i is the amplitude, τ is the lifetime, and C is an offset. Error bars for the lifetimes are reported as standard errors of the exponential fits. […]

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MM quadruply bonded complexes supported by vinylbenzoate ligands: synthesis, characterization, photophysical properties and application as synthons††Electronic supplementary information (ESI) available: Transient absorption plots and kinetics, time resolved IR plots, NIR emission. CCDC 1015787 and 1015788. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc02542cClick here for additional data file.Click here for additional data file.

2015 Chemical Science
PMCID: 4583209
PMID: 26417424
DOI: 10.1039/c4sc02542c

Pipeline specifications

Software tools GaussView, SHELX, SigmaPlot
Applications Drug design, Miscellaneous, Protein structure analysis
Organisms Dipturus trachyderma
Chemicals Carbon, Molybdenum, Toluene, Tungsten