The Suzuki-Miyaura cross-coupling reaction has successfully been applied for the synthesis of 4,4'- [6-(diethylamino)-1,3,5-triazine-2,4-diyl]diphenol (4a), 4,4'-(pyrimidine-4,6-diyl)diphenol (4b), 4,4'-(pyridine-2,6-diyl)diphenol (4c). The reaction of 4,6-dichloro-N,N-diethyl-1,3,5-triazin-2-amine (1a), 4,6-dichloropyrimidine (1b) and 2,6-dichloropyridine (1c) with p-methoxyphenylboronic acid (2) in the presence of palladium catalyst followed by demethylation reaction furnished the desired products in good to excellent yields. To test the reactivity of these nucleophiles, the compound 4a was further reacted with cyanuric chloride to get trimeric fragment (5a). All the compounds were characterized by their physical, spectral (¹H and 13C NMR and Mass) and microanalytical data. These dinucleophilic fragments (4a-4c) having triazine, pyrimidine and pyridine rings, respectively, are excellent future candidates for the construction of large functional hetero-atom bridged macrocycles for diverse applications in host-guest chemistry, supramolecular catalysis, self-assembly and other related fields of supramolecular chemistry in addition to their potential in medicinal chemistry.

A síntese e o comportamento de fase de três novos polímeros cristais líquidos de cadeia lateral são descritos. Os novos polímeros apresentaram mesofase esmética C (SmC). O estudo de raios X para duas amostras revelou parcial interdigitação para a mesofase SmC do polímero com espaçador mais curto, enquanto que com espaçador mais longo o polímero não apresentou interdigitação.

The synthesis and phase behavior of three new side-chain liquid crystal polymers with short and long flexible alkyl spacers are described. These new materials show smectic C (SmC) mesophase. X-ray analysis for two samples has revealed that SmC mesophase displays partial interdigitation for the polymer with short flexible spacer, while for long flexible spacer polymer no interdigitation was observed.

Background: The Bemisia tabaci is one of the most devastating pests of agricultural crops and ornamental plants worldwide. The genetic diversity and biotype status of the Bemisia tabaci in Pakistan was assessed by using random amplified polymorphic DNA-polymerase chain reaction (RAPD-PCR). A total 80 samples of B. tabaci collected from 14 districts of the Punjab province and 7 districts of the Sindh province were included. Results: All 10 primers screened in this study generated 151 scorable amplification products, of which 117 or 77% were polymorphic. Pairwise Nei and Li’s similarity had ranged from 0.25 to 0.88 among all individuals analyzed. Based on Nei and Li’s similarity coefficients Bemisia populations were grouped into 3 main clusters and clearly distinguished the non B biotype from the B biotype. Conclusion: The level of similarity among populations of same biotypes was high whereas between populations of non B and B biotypes appeared to be less closely related. This analysis showed that non B biotype is prevalent in both provinces however B biotype is restricted to few locations in Sindh. This monitoring of the spread of B. tabaci in Pakistan will assist in the establishment of appropriate management strategies.