“…The shift of this peak from the uncoordinated condensed-phase phosphoryl stretch at about 1246 cm -1 is taken as evidence for coordination of DMMP to the copper atom via its phosphoryl oxygen. The observed downshift is consistent with previous studies that reported a shift in the phosphoryl peak from ∼1250 cm -1 (uncoordinated) to values between 1166 and 1212 cm -1 upon coordination of DMMP to metal ions or upon adsorption of DMMP onto metal oxide surfaces. − 3 Lower-wavenumber IR spectra of a thin film of 8CB on a carboxylic acid-terminated SAM surface supporting copper(II) perchlorate salts (a) before and (b) during exposure to 10 ppm DMMP and (c) after a 30-min air purge.…”
Section: Resultssupporting
confidence: 89%
“…We placed the samples into a gastight chamber built to fit within the PM-IRRAS instrument and obtained IR spectra with modulation centered at 2200 cm -1 (nitrile stretching region). For convenience, a summary of spectral assignments used in this study can be found in Table . − …”
Section: Resultsmentioning
confidence: 99%
“…After a 30-min purge in air (Figure c), the peak corresponding to the nickel-coordinated nitrile was observed to recover, as was also the case with the copper-coordinated nitrile (Figure c). We note that spectral assignments for 8CB supported on nickel(II) perchlorate salts are listed in Table . − 4 Middle-wavenumber IR spectra of a thin film of 8CB on a carboxylic acid-terminated SAM surface supporting nickel(II) perchlorate salts (a) before and (b) during exposure to 10 ppm DMMP and (c) after a 30-min air purge.…”
We report the use of Fourier transform polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to characterize the influence of dimethyl methylphosphonate (DMMP) on the molecular interactions occurring within thin films of nitrile-containing liquid crystals supported on surfaces presenting metal perchlorate salts. Infrared spectra obtained using thin films of 4'-octyl-4-biphenylcarbonitrile (8CB) supported on copper(II) perchlorate salts reveal the nitrile groups of 8CB to be coordinated to the copper(II) on these surfaces, and subsequent exposure of the system to DMMP to result in the elimination of these coordinated nitrile groups. Concurrently, evidence of coordination of the phosphoryl group of DMMP with copper(II) is provided by measurement of a shift of the phosphoryl stretch from 1246 to 1198 cm(-1). In contrast, surfaces presenting nickel(II) perchlorate salts only weakly coordinate with DMMP [the phosphoryl peak shifts from 1246 to 1213 cm(-1) in the presence of nickel(II)], and exposure of 8CB to DMMP results in only partial loss of coordination of the nitrile groups of 8CB with nickel(II). These PM-IRRAS measurements and others reported in this article provide insights into the molecular origins of macroscopic ordering transitions that are observed when micrometer-thick films of nitrile-containing liquid crystals supported on copper(II) or nickel(II) perchlorate are exposed to DMMP: Upon exposure to DMMP, nematic phases of 4'-pentyl-4-biphenylcarbonitrile (5CB) supported on copper(II) perchlorate salts undergo ordering transitions, whereas 5CB supported on nickel(II) perchlorate salts do not. Our IR results support the hypothesis that these ordering transitions reflect the relative strengths of coordination interactions occurring between the 5CB, DMMP, and the metal salts at these interfaces.
“…The shift of this peak from the uncoordinated condensed-phase phosphoryl stretch at about 1246 cm -1 is taken as evidence for coordination of DMMP to the copper atom via its phosphoryl oxygen. The observed downshift is consistent with previous studies that reported a shift in the phosphoryl peak from ∼1250 cm -1 (uncoordinated) to values between 1166 and 1212 cm -1 upon coordination of DMMP to metal ions or upon adsorption of DMMP onto metal oxide surfaces. − 3 Lower-wavenumber IR spectra of a thin film of 8CB on a carboxylic acid-terminated SAM surface supporting copper(II) perchlorate salts (a) before and (b) during exposure to 10 ppm DMMP and (c) after a 30-min air purge.…”
Section: Resultssupporting
confidence: 89%
“…We placed the samples into a gastight chamber built to fit within the PM-IRRAS instrument and obtained IR spectra with modulation centered at 2200 cm -1 (nitrile stretching region). For convenience, a summary of spectral assignments used in this study can be found in Table . − …”
Section: Resultsmentioning
confidence: 99%
“…After a 30-min purge in air (Figure c), the peak corresponding to the nickel-coordinated nitrile was observed to recover, as was also the case with the copper-coordinated nitrile (Figure c). We note that spectral assignments for 8CB supported on nickel(II) perchlorate salts are listed in Table . − 4 Middle-wavenumber IR spectra of a thin film of 8CB on a carboxylic acid-terminated SAM surface supporting nickel(II) perchlorate salts (a) before and (b) during exposure to 10 ppm DMMP and (c) after a 30-min air purge.…”
We report the use of Fourier transform polarization modulation infrared reflection-absorption spectroscopy (PM-IRRAS) to characterize the influence of dimethyl methylphosphonate (DMMP) on the molecular interactions occurring within thin films of nitrile-containing liquid crystals supported on surfaces presenting metal perchlorate salts. Infrared spectra obtained using thin films of 4'-octyl-4-biphenylcarbonitrile (8CB) supported on copper(II) perchlorate salts reveal the nitrile groups of 8CB to be coordinated to the copper(II) on these surfaces, and subsequent exposure of the system to DMMP to result in the elimination of these coordinated nitrile groups. Concurrently, evidence of coordination of the phosphoryl group of DMMP with copper(II) is provided by measurement of a shift of the phosphoryl stretch from 1246 to 1198 cm(-1). In contrast, surfaces presenting nickel(II) perchlorate salts only weakly coordinate with DMMP [the phosphoryl peak shifts from 1246 to 1213 cm(-1) in the presence of nickel(II)], and exposure of 8CB to DMMP results in only partial loss of coordination of the nitrile groups of 8CB with nickel(II). These PM-IRRAS measurements and others reported in this article provide insights into the molecular origins of macroscopic ordering transitions that are observed when micrometer-thick films of nitrile-containing liquid crystals supported on copper(II) or nickel(II) perchlorate are exposed to DMMP: Upon exposure to DMMP, nematic phases of 4'-pentyl-4-biphenylcarbonitrile (5CB) supported on copper(II) perchlorate salts undergo ordering transitions, whereas 5CB supported on nickel(II) perchlorate salts do not. Our IR results support the hypothesis that these ordering transitions reflect the relative strengths of coordination interactions occurring between the 5CB, DMMP, and the metal salts at these interfaces.
A number of anhydrous cobalt(II), nickel(II), and copper(II) tetrafluoroborate complexes of the ligands trimethyl phosphate, triethyl phosphate, triallyl phosphate, dimethyl methylphosphonate, diisopropyl methylphosphonate, dibutyl butylphosphonate and O,P‐dimethyl‐P‐phenylphosphinate have been prepared using a two step preparative procedure via the methanol complexes. For this type of ligand, this method gives better results than the usual one step procedure. The complexes are characterized with the aid of physical measurements such as ligand‐field spectroscopy.
Reaktionen von Metallthiocyanaten der 3d‐Reihe mit ausgewählten Aminoacridin‐N‐oxiden führen aus homogenen N,N‐Dimethylformamidlösungen zu Verbindungen der Typen [M(AAcNO)a(DMF)b(NCS)2] · cDMF und [M′(AAcNO)d(DMF)e(NCS)3] · fDMF, M7dbond;Mn2+, Co2+, Ni2+, Cu2+, Zn2+; M′ = Cr3+, Fe3+; AAcINO = 3,6‐Diamino‐2,7‐dimethylacridin‐N‐oxid, AAcIINO = 3,6‐Bis(dimethylamino)acridin‐N‐oxid, AAcIIINO = 2‐Ethoxy.6,9‐diaminoacridin‐N‐oxid; a = 1, 2, 3, 4; b = 0, 1; c = 0, 1, 2, 3; d = 1, 2, 3; e = 0, 1, 2 und f = 0, 1, 2, 3.
Die dargestellten Komplexe werden durch die IR (4000–200 cm−1) und UV‐VIS‐Spektren von Lösungen und Festkörpern sowie durch EPR‐ und Leitfähigkeitsuntersuchungen näher charakterisiert.
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