HPLC analysis of polycarboxylic acids used as durable press finishing agents/ organic catalysts for cellulosic material

Cotton fabric is modified by means of polycarboxylic acids in combination with an inorganic or an organic catalyst in order to impart durable press properties. After the curing process the cellulosic specimen is washed off to remove both the portion of the polycarboxylic acid that has not reacted and the catalyst applied. The treated cellulosic fabric is saponified with a sodium hydroxide solution to extract the PCA that has reacted with the cellulosic material. Both the wash liquor and the saponification liquor are investigated by means of isocratic HPLC using Aminex HPX-87-H as stationary phase. Excellent separation of the various polycarboxylic acids that are applied as crosslinking agents or as organic catalysts is achieved. The HPLC method presented enables the identification and quantification of the polycarboxylic acids. Received: 19 January 1999 / Revised: 24 March 1999 / Accepted: 28 March 1999     

Synthesis and Structure of 1,2-Diphenyl-1,2-disila-closo-dodecaborane(12), Reaction with [Zr(NMe2)4] and [Ta(NMe2)5]

Diphenyl-o-silaborane ( 1 ) can be obtained by sublimation as colourless crystalline material in a yield of 23%. The disilaborane 1 was characterized by NMR spectroscopy, mass spectrometry and X-ray structure analysis. The neutral closo cluster 1 reacts with [Zr(NMe₂)₄] or [Ta(NMe₂)₅] to give the dimethylamide adduct [(Me₂N)(PhSi)₂B₁₀H₁₀]^– of the disilaborane.     

Octamethyl‐1, 1′‐di(2‐pyridyl)ferrocene: A Redox‐Active Ligand with a Pronounced Selectivity for Divalent Metal Ions

Octamethyl‐1, 1′‐di(2‐pyridyl)ferrocene ( 1 ) acts as molecular electrochemical sensor for magnesium, calcium, zinc, and cadmium ions in acetonitrile solution. The new redox peak, anodically shifted by ca. 0.40 V, which appears in the cyclic voltammogram of 1 in the presence of even small amounts (10 mol %) of these ions, is unaffected by an excess of alkali metal ions. Metal complexation is accompanied by a batho‐ and hyper‐chromic shift of the band in the visible region of the UV‐Vis spectrum of 1 . A detailed study of the behaviour of 1 towards zinc chloride in acetonitrile solution has revealed that 1 is able to accommodate a maximum of two zinc ions. Oxidation of zinc‐coordinated 1 leads to partial decomplexation. The N‐methyl and N‐benzyl species 1 Me⁺, 1 Me₂²⁺, 1 Bzl⁺ and 1 Bzl₂²⁺ have been synthesized and the former two structurally investigated by X‐ray diffraction. Alkylation causes an anodic shift of the redox potential of the ferrocene nucleus, which is linearly dependent on the number of alkyl groups introduced. Octamethyl‐1, 1′‐di(2‐thiophenyl)ferrocene ( 2 ) has also been synthesized and structurally characterized by X‐ray diffraction. Cyclic voltammetry has revealed that, in contrast to 1 , 2 does not respond to the divalent metal ions studied.     

A Rational Approach to Tetra-Functional Photo-Switches

α,ω-Bis(1,8-dichloroanthracen-10-yl)alkanes with (CH₂)_n-linker units (n=1–4) were synthesized starting from 1,8-dichloroanthracen-10(9H)-one. This was transformed into anthracenes with allyl, bromomethyl and propargyl substituents in position 10; these were converted in various C−C-bond formation reactions (plus hydrogenation), leading to two anthracene units flexibly linked by α,ω-alkandiyl groups. 1,2-Ethandiyl- and 1,3-propandiyl-linked derivatives were functionalized with ethynyl groups in positions 1, 8, 1’ and 8’, and these terminally functionalized by Me₃Sn groups using Me₂NSnMe₃. All linked bisanthracenes were subjected to UV light induced cyclomerization and a series of 9,10 : 9’,10’-photo-cyclomers were obtained. Their thermal cycloreversion and (repeated) switchability was demonstrated. 1,3-Bis{1,8-bis[(trimethylstannyl)ethynyl]anthracen-10-yl}propane served as model compound for photo-switchable acceptor molecules and its open and closed forms were characterized by NMR and DOSY experiments.     

Modal properties of all-active InGaAsP/InP microring lasers

An experimental investigation of the multimode dynamics of 1.55 μm-InGaAsP/InP microring lasers is demonstrated. Different operation regimes are observed, bidirectional multimode, unidirectional single mode, bidirectional single mode and mode-hopping. The extent of each of the above operation regimes is examined with respect to the ring current level, bus waveguide reflectivity and ring radius. The back-reflections generated from the bus waveguide facets are indirectly controlled via the bus waveguide current. In order to clarify the physical mechanisms beyond experimental results, a multimode model based on the rate equation approximation is utilized. The experimental results are in good agreement to those predicted by the multimode model.