- Tuning the lifetime of transient phases of mechanochromic gold isocyanide complexes through functionalization of the terminal moieties of flexible side chains
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The lifetime of the transient phases of luminescent mechanochromic gold isocyanide complexes could be tuned through the modification of the termini of flexible side chains. Upon grinding, these complexes initially showed an emission color change from blue to yellow. The yellow emission spontaneously changed to blue or green, but with different lifetimes of the yellow-emitting transient phases depending on the substituents. Details of the mechano-induced structure changes were also described.
- Seki, Tomohiro,Kashiyama, Kentaro,Yagai, Shiki,Ito, Hajime
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- Combinatorial synthesis of PEG oligomer libraries
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A simple chain-extending approach was established for the scale-up of the monoprotected monodisperse PEG diol materials. Reactions of THP-(OCH2CH2)n—OMs (n=4, 8, 12) with a large excess of commercially available H—(OCH2CH2)n—OH (n=1-4) under basic conditions led to THP-(OCH2CH2)n—OH (n=5-15). Similarly, Me-(OCH2CH2)n—OH (n=4-11, 13) were prepared from Me-(OCH2CH2)n—OMs (n=3, 7, 11). For the chain elongation steps, 40-80% yields were achieved through extraction purification. PEG oligomer libraries I and II were generated in 50-95% overall yields by alkylation or acylation of THP-(OCH2CH2)n—OH (n=1-15) followed by deprotection. Alkylation of Me-(OCH2CH2)n—OH (n=1-11, 13) with X—(CH2)m—CO2R (X=Br or OMs) and subsequent hydrolysis led to PEG oligomer library III in 30-60% overall yields. Combinatorial purification techniques were adapted to the larger-scale library synthesis. A total of 498 compounds, each with a weight of 2-5 g and a minimum purity of 90%, were synthesized.
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Page/Page column 9
(2010/02/15)
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- Self-assembling properties of non-ionic tetraphenylporphyrins and discotic phthalocyanines carrying oligo(ethylene oxide) alkyl or alkoxy units
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The thermotropic phase behaviour and self-assembling features of some non-ionic tetraphenylporphyrins and phthalocyanines containing oligo(ethylene oxide) alkoxy or alkyl units have been investigated. From DSC measurements and polarization microscopy it was concluded that none of the tetraphenylporphyrins was mesomorphic while the phthalocyanines displayed discotic hexagonal phases even at room temperature. The aggregation of the compounds in aqueous media was studied by means of UV-VIS and fluorescence spectroscopy and it has been found that in water the tetraphenylporphyrins form J- or head-to-tail type of aggregates while phthalocyanines form H- or face-to-face type of aggregates. The luminescence properties of the tetraphenylporphyrin and phthalocyanine aggregates are explained on the basis of the molecular exciton approximation. Steric constraints and orientational disorder in the tetraphenylporphyrin aggregates determine the luminescence yield relative to the monomeric species. The cofacial arrangement of the macrocycles in phthalocyanine aggregates results in a forbidden S1-S0 transition and thus in a complete disappearance of the luminescence.
- Kroon, Johannes M.,Koehorst, Robert B. M.,Van Dijk, Marinus,Sanders, Georgine M.,Sudhoelter, Ernst J. R.
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p. 615 - 624
(2007/10/03)
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- Process for preventing consolidation of p-dichlorobenzene
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A triethylene glycol derivative is added to p-dichlorobenzene so as to prevent consolidation and improve flowability of p-dichlorobenzene.
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- Topical mosquito repellents VII: Alkyl triethylene glycol monoethers
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Normal and branched chain aliphatic monoethers of triethylene glycol are effective topical mosquito repellents. In terms of duration of protection, they are generally superior to the corresponding diethylene glycol analogs, and some are superior to diethyltoluamide. The n heptyl monoether of triethylene glycol affords double the protection time of diethyltoluamide under controlled laboratory conditions, and appears to be a useful new mosquito repellent.
- Johnson,DeGraw,Engstrom,Skinner,Brown,Skidmore,Maibach
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p. 693 - 695
(2007/10/05)
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