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141.
Belcher WJ Longstaff CA Neckenig MR Steed JW 《Chemical communications (Cambridge, England)》2002,(15):1602-1603
A new channel-containing 1D coordination polymer has been prepared by the combination of a linear dimetallic spacer, Cu2(O2CMe)4, and a linear didentate ligand, 1,3-di-4-pyridylpropane; the new material includes methanol, acetic acid and diethylene glycol. 相似文献
142.
143.
P. Robb P. Warwick D. J. Malcolme-Lawes 《Journal of Radioanalytical and Nuclear Chemistry》1985,89(2):323-329
A method is described which can be used to determine technetium-99 levels in a range of water types. Ruthenium isotopes which may interfere in the analysis are removed from the sample by precipitation before concentration of pertechnetate onto an ion-exchange column. Other nuclides can be removed from the column using NaOH before elution of the technetium using NaSCN. The technetium in the NaSCN eluent can then be extracted into butan-2-one which can be evaporated onto a planchette. Technetium-99m is used as a yield tracer and after this has decayed away to negligible levles the amount of technetium on the planchette can be determined by measuring the rate of beta radiation emission from the final concentrate. 相似文献
144.
McKenzie K Grosse N Bowen WP Whitcomb SE Gray MB McClelland DE Lam PK 《Physical review letters》2004,93(16):161105
We demonstrate the generation of broadband continuous-wave optical squeezing from 280 Hz-100 kHz using a below-threshold optical parametric oscillator (OPO). The squeezed state phase was controlled using a noise locking technique. We show that low frequency noise sources, such as seed noise, pump noise, and detuning fluctuations, present in optical parametric amplifiers, have negligible effect on squeezing produced by a below-threshold OPO. This low frequency squeezing is ideal for improving the sensitivity of audio frequency measuring devices such as gravitational-wave detectors. 相似文献
145.
The photochemistry of poly{p-phenylene[1-(tetrahydrothiophen-1-io)ethylene chloride]} (PPTEC), a water soluble precursor of the semiconducting polymer, poly{p-phenylenevinylene} (PPV), has been studied both under atmospheric conditions and in environments devoid of oxygen. UV-visible spectroscopy and photoluminescence data has been used to provide a picture of the mechanistic pathways involved in UV irradiation of the PPTEC material. A new quantitative model for the effect of UV irradiation upon film morphology is presented, which leads to insights for the improved control of the characteristics of PPV nanostructures produced via near-field scanning optical lithography. 相似文献
146.
147.
Annika C. S. Page Spencer O. Scholz Katherine N. Keenan Jessica N. Spradlin Bridget P. Belcher Scott M. Brittain John A. Tallarico Jeffrey M. McKenna Markus Schirle Daniel K. Nomura F. Dean Toste 《Chemical science》2022,13(13):3851
Photoaffinity labeling (PAL) is a powerful tool for the identification of non-covalent small molecule–protein interactions that are critical to drug discovery and medicinal chemistry, but this approach is limited to only a small subset of robust photocrosslinkers. The identification of new photoreactive motifs capable of covalent target capture is therefore highly desirable. Herein, we report the design, synthesis, and evaluation of a new class of PAL warheads based on the UV-triggered 1,2-photo-Brook rearrangement of acyl silanes, which hitherto have not been explored for PAL workflows. Irradiation of a series of probes in cell lysate revealed an iPr-substituted acyl silane with superior photolabeling and minimal thermal background labeling compared to other substituted acyl silanes. Further, small molecule (+)-JQ1- and rapamycin-derived iPr acyl silanes were shown to selectively label recombinant BRD4-BD1 and FKBP12, respectively, with minimal background. Together, these data highlight the untapped potential of acyl silanes as a novel, tunable scaffold for photoaffinity labeling.Irradiation initiated 1,2-photo Brook rearrangement of acyl silanes generated α-siloxycarbene intermediates that were used for photoaffinity labeling. Optimization of the acyl silane group produced a probe capable of capturing small molecule–protein interactions. 相似文献
148.
A total of 181 vertical ionization potentials (VIPs) of 41 molecules were calculated by density functional theory (DFT) employing the Perdew–Wang 1986 (PW86) exchange and Perdew–Wang 1991 (PW91) correlation functionals and using the aug‐cc‐pV5Z basis and experimental ground‐state geometries. The overall average absolute deviation (AAD) from experiment was found to be 0.55 eV and only 0.31 eV for linear molecules but 0.86 eV for nonplanar molecules. A number of VIPs were in error by over 2 eV. In particular, DFT performed most poorly when ionization was from an orbital with highly varying density gradients (which arise from the orbital's shape or compactness or through its density being distributed over a number of atoms). Indications are that many or all present‐day functionals suffer from the same failings. © 2001 John Wiley & Sons, Inc. Int J Quant Chem 81: 34–52, 2001 相似文献
149.
We investigate a one-parameter family of interval maps arising in the study of the geometric Lorenz flow for non-classical
parameter values. Our conclusion is that for all parameters in a set of positive Lebesgue measure the map has a positive Lyapunov
exponent. Furthermore, this set of parameters has a density point which plays an important dynamic role. The presence of both
singular and critical points introduces interesting dynamics, which have not yet been fully understood. 相似文献
150.
Warwick J. Belcher Matthis Breede Penelope J. Brothers Clifton E. F. Rickard 《Angewandte Chemie (International ed. in English)》1998,37(8):1112-1114
A new coordination mode for the porphyrin ligand is found in [B2O2(BCl3)2(tpClpp)] (tpClpp=dianion of 5,10,15,20-tetra-p-chlorophenylporphyrin; the p-chlorophenyl groups are omitted for clarity in the picture shown on the right). This complex contains a four-membered B2O2 ring in the cavity of the ligand. The two boron atoms are coplanar with the porphyrin molecule, which undergoes an elongation along the B⋅⋅⋅B axis to accomodate the unusual guest. 相似文献