Approximately 50 mg of solid samples was accurately weighed and transferred to a 1.5 ml Eppendorf reaction tube, 1 ml of deuterated DMSO containing 0.05% tetramethylsilane
[sup.1]H NMR (300.1 MHz) spectra were recorded on a Bruker spectrometer in [DMSO-d.sub.6] as a solvent using tetramethylsilane
([Me.sub.4]Si) as internal standard.
Samples were prepared at 5 wt% in deuterated chloroform ([CDC1.sub.3]) containing 0.03 vol% tetramethylsilane
(TMS) as an internal standard.
(TMS) served as the internal standard.
Air drying after preparation in organic compounds with low surface tension such as Peldri II (Brown 1990), hexamethyldisilazane (HMDS) (Nation 1983), tetramethylsilane
(TMS) (Dey et al.
Dehydrated material was left in tetramethylsilane
overnight, allowed to air dry, and then was sputter coated in gold and observed on a JEOL 35 SEM.
NMR spectra were recorded with a spectrometer (400.13 MHz [sup.1]H) in CD[Cl.sub.3] with chemical shifts referenced to tetramethylsilane
The [sup.1]H NMR spectra were recorded on a Varian Gemini 200 or a Varian INOVA 400 (Varian Inc., Walnut Creek, CA) by using C[D.sub.2][Cl.sub.2] or CD[Cl.sub.3] (Cambridge Isotope Laboratories, Inc., Andover, MA) as a solvent and tetramethylsilane
as an internal standard.
The chemical shift is given relative to tetramethylsilane
(TMS = 0 ppm) scale.
[sup.1]H and [sup.13]C chemical shifts ([delta]) are reported in ppm relative to the internal standard tetramethylsilane
(TMS; [delta] = 0) in CD[Cl.sub.3] ([delta] = 7.26 for [sup.1]H, 77.02 for [sup.13]C) or relative to residual CHD20D ([delta] = 3.30 ppm for [sup.1]H) or C[D.sub.3]OD (49.0 for [sup.13]C), whereas H,H scalar couplings (J) are given in Hz.
was used as an internal standard; the chemical shifts are reported in ppm relative to it in all cases.
1H-and 13C-NMR spectra: Bruker spectrometers operating at 500 MHz and 125 MHz respectively, chemical shifts (I') in ppm relative to tetramethylsilane
as international standard and J value in Hz.