The influence of pentafluorophenyl groups on the nonlinear optical (NLO) performance of high generation dendrons and dendrimers
With the aim to make the influence of pentafluorophenyl groups in the periphery of high generation dendrons and dendrimers on their NLO performance clearly, some NLO dendrons and dendrimers with different chromophore moieties or different end-capped groups were carefully designed and investigated in detail. The results demonstrated that some strong Ar-ArF interactions between the pentafluorophenyl groups in the periphery and the normal phenyl rings of the donors, could influence the topological structures of dendrons or dendrimers, and then affect their NLO performance. Furthermore, the optical transparency and the stability of the dendrons and dendrimers with pentafluorophenyl groups as end-capped moieties were all improved, in comparison with normal dendrons and dendrimers containing phenyl ones as the end-capped groups.
A fast track strategy toward highly functionalized dendrimers with different structural layers: an “onion peel approach”
An accelerated strategy depending on different chemical building blocks between each layer, coined “onion peel”, was used to construct a library of third generation dendrimers with 108, 180 and 252 hydroxyl surface groups using a combination of microwave assisted highly efficient CuAAC and thiol–ene reactions. These dendrimers were conveniently acquired with high purity and good yields in a divergent manner using a variety of orthogonal and dense AB3, AB5, and AB7 building blocks. The resulting polyhydroxylated dendrimers tested in several human cell types did not impair mitochondrial metabolic function or cell viability suggesting that they are good candidates for applications in biological investigations.
Archaeology and mud wall decay in a West African village
Abstract A detailed study of the processes of deterioration of mud walls and of the physical evolution and devolution of a contemporary West African village is seen to facilitate the location of decayed mud structures at a nearby archaeological site. Various climatic and pedological conditions at the site make it unlikely that such walls will be discerned. The archaeologist wishing to obtain the fullest and least biased picture of the settlement configuration of the ancient community should therefore heed all the inferential lessons to be had from a focused ethnographic investigation. Given similar climatic situations and practices of house construction, taphonomy and ethnographic analogies may both be necessary for a valid reconstruction of an archaeological settlement.