Diamine spacer

Halogenation of pyrimidine bases may be done with bromine or iodine. Bromination occurs at the C-5 of cytosine, yielding a reactive derivative, which can be used to couple diamine spacer molecules by nucleophilic substitution (Figure 1.48) (Traincard et al., 1983 Sakamoto et al., 1987 Keller et al., 1988). Other pyrimidine derivatives also are reactive to bromine compounds... 

Cascade Blue cadaverine and Cascade Blue ethylenediamine both contain a carboxamide-linked diamine spacer off the 8-methoxy group of the pyrene trisulfonic acid backbone. The cadaverine version contains a 5-carbon spacer, while the ethylenediamine compound has only a 2-carbon arm. Both can be coupled to carboxylic acid-containing molecules using a carbodiimide reaction (Chapter 3, Section 1). Since Cascade Blue derivatives are water-soluble, the carbodiimide EDC can be used to couple these fluorophores to proteins and other carboxylate-containing molecules in aqueous solutions at a pH range of 4.5-7.5. The reaction forms amide bond linkages (Figure 9.39). 

Quantitative Determination of Coupied Diamine Spacers with 2,4,6-Trinitrobenzene Suifonic Acid... 

Dications such as (95) can be prepared electrochemically as shown, and can be isolated as their di-BF4 salts following treatment with HBF4.138 Reaction of species such as (96) with 1,4-diaminobenzene leads to new bis(pentadienylium) dications with a phenylene-1,4-diamine spacer, which are dyes with interesting optical properties.139... 

Another prodrug of 54c is compound 55. Prodrug 55, which contains an aromatic and aliphatic bis-carbamate spacer, is activated by (3-glucuronidase (Scheme 23).86 A rapid cleavage of the glycosidic bond occurred (tj/2 = 6.6 minutes) with concomitant appearance of intermediate 55c, of which the ethylene diamine spacer cyclized with a half-life of 2 hours. The cytotoxicity of 55 against LoVo cells was about 50 times less than that of the corresponding phenol mustard 54c. 

Kricheldorf has reported the synthesis of lyotropic poly(amide-imide)s and poly(benzoxazole-amide)s. These were prepared by the polycondensation of N,N-bis(trimethylsilyl)-p-phenylenediamine or N,AT -bis(trimethylsilyl)-3,3 -dim-ethylbenzidine with the diacyl chloride of trimellitimide of p-aminobenzoic acid, or the imide formed from p-amino benzoic acid and terephthalic acid. Lyotropic behaviour was observed in cone, sulphuric acid solution [38]. A series of thermotropic poly(imide-amide)s was prepared based on trimellitimides formed from trimellitic anhydride and an a, -bis(4-aminophenoxy) alkane with carbon chain lengths 9-12. Melting points were in the range 250-300 °C. They formed smectic A phases and tended to degrade around the isotropisation temperatures (around 350 °C). Pendant methyl groups or occupied meta- groups tended to prevent mesophase formation [39]. Novel LC poly(imide-amides) have also been synthesised from new diamine spacers derived from linear diaminoalkanes and 4-nitrophthalic anhydride. A smectic and nematic phase were observed when 4,4 -biphenyl dicarboxylic acid was used as co-monomer [40]. 

A new class of diamine spacer was synthesised from a,co-diaminoalkanes and 4-nitrophthalic anhydride the resulting a, -bis(4-aminophthalimido)alkanes were polycondensed with one of the following acid chlorides terephthaloylchlo-ride, 2-phenylthioterephthaloylchloride, naphthalene-2,6-dicarboxylic acid or 4,4 -biphenyldicarboxylic acid chloride [40]. Thermotropic behaviour was con-... 

Effect of Diamine Spacer Length on Composite Fracture Toughness... 

Interested by the effect of other structural modifications on the thermal behavior, and the possibility to combine several metal centers within the same compound, Swager and co-workers pursued this research, and reported series of homo-dinuclear, hetero-dinuclear 1,3,5-triketonate (79), and 1,3,5,7-tetraketonate Schiff-base complexes (80). " Providing a minimum of at least six lateral chains and short diamine spacers ((79) M, M = Cu, Ni, Mn, Pd, Co X = C2H4, CsHg), complexes (79) displayed Colh mesophases, being as such the first heterodinuclear metallomesogens (Table 48). The mesophase existed over broader temperature ranges than those of the related... 

Smith, Hirst and co-workers reported the effect of the aliphatic diamine spacer chain length on the supramolecular chiral assembly [72], Interestingly, the degree of structuring observed in these gel-phase materials was directly controlled by the length of the diamine spacer unit, as illustrated by the thermally reversible gel-sol phase transition (Tgei). Remarkably, as the length of... 

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