A Global View on Block Copolymers

In this systematic review, a total of 45,143 publications on block copolymers, issued between 1952 and 2019, are analyzed in terms of number, source, language, institution, country, keywords, and block copolymer type, to find out their evolution and predict research trends. The number of publications devoted to block copolymers has been growing for over six decades, maintaining a consistent level throughout the last few years. In their majority, documents came out of the United States, although more recently, Chinese institutions are those displaying the largest production. Keywords analysis indicated that one-third of the publications concerned synthesis, around 20% explored self-assembly and morphological aspects, and another 20% referred to block copolymer applications in solution. In particular, 2019 confirmed the expansion of studies related to drug delivery, and in minor extent, to a deeper view of self-assembling. Styrene–butadiene–styrene block copolymer was the most popular in studies covering both basic and industrially oriented aspects. Other highly investigated copolymers are PEO-b–PPO-b–PEO (Pluronic©) and amphiphilic block copolymers based on polycaprolactone or poly(lactic acid), which owed their success to their potential as delivery vehicles. Future trending topics will concern nanomedicine challenges and technology-related applications, with a special attention toward the orientation and ordering of mesophase-separated morphologiesThis research was funded by the Spanish Agencia Estatal de Investigación (PGC2018-101047). M.L. also acknowledges the Xunta de Galicia (Grupo con Potencial de Crecemento ED431B 2018/1 and Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03) and the European Union (European Regional Development Fund-ERDF)S

Some Guidelines for the Synthesis and Melting Characterization of Azide Poly(ethylene glycol) Derivatives

We provide fundamental guidelines in the form of a tutorial to be taken into account for the preparation and characterization of a specific class of poly(ethylene glycol) (PEG) derivatives, namely azide-terminated PEGs. Special attention is given to the effect of these chain end groups and their precursors on properties affecting the PEGylation of proteins, nanoparticles and nanostructured surfaces. Notwithstanding the presence of 13C satellite peaks, we show that 1H NMR enables not only the routine quantitative determination of chain-end substitution, but is also a unique method to calculate the absolute number average molecular weight of PEG derivatives. In the use of size exclusion chromatography to get molecular weight distributions, we highlight the importance of distinguishing between eventual secondary reactions involving molecular weight changes and the formation of PEG complexes due to residual amounts of metal cations from reactants. Finally, we show that azide end groups affect PEG melting behavior. In contrast to oxygen-containing end groups, azides do not interact with PEG segments, thus inducing defect formation in the crystal lattice and the reduction of crystal sizes. Melting temperature and degree of crystallinity decrease become especially relevant for PEGs with very low molecular weight, and its comprehension is particularly important for solid-state applicationsThis research was funded by the Spanish Agencia Estatal de Investigación (PGC2018-101047). M.L. also acknowledges the Xunta de Galicia (Grupo con Potencial de Crecemento ED431B 2018/1 and Centro singular de investigación de Galicia accreditation 2019-2022, ED431G 2019/03) and the European Union (European Regional Development Fund-ERDF)S

Sintesis de analogos de la vitamina D funcionalizados en las posiciones C-11 y C-24

Available from Centro de Informacion y Documentacion Cientifica CINDOC. Joaquin Costa, 22. 28002 Madrid. SPAIN / CINDOC - Centro de Informaciòn y Documentaciòn CientìficaSIGLEESSpai

Probing the Versatility of Shape-Persistent Tetraphenylmethane Dendrimers by Modification of the Skeleton

Tetraphenylmethane has emerged as a recurrent building block for advanced porous materials such as COFs, PAFs and hypercrosslinked polymers. Guided by a similar design principle, we have previously synthesized shape-persistent dendrimers with tetraphenylmethane nodes and ethynylene linkers. Here we report the generality of our approach by describing new dendritic architectures built from tetraphenylmethane. First, we prepared expanded dendrimers where the tetrahedral units are bonded through larger rigid rod spacers. Among the different synthetic strategies tested, the convergent route, with alternating steps of Pd-catalyzed Sonogashira coupling and alkyne activation by removal of TMS masking groups, efficiently afforded the first- and second-generation dendrimers. A second type of compounds having a linear diyne at the core is also described. The dendrimers of generations 1-2 were also synthesized by a convergent approach, with the diyne being assembled in the last step of the synthesis by a Glaser oxidative homocoupling of the corresponding dendrons bearing a terminal alkyne at the focal point. A third-generation dendrimer was also successfully prepared by a double-phase strategy.<br /

Synthesis and biological evaluation of 1α,25-dihydroxyvitamin D 3 analogues hydroxymethylated at C-26

We designed by docking and synthesized two novel analogues of 1α,25-dihydroxyvitamin D3 hydroxymethylated at C-26 (2 and 3). The syntheses were carried out by the convergent Wittig-Horner approach via epoxide 12a as a common key intermediate. The antiproliferative and transactivation potency of the compounds was evaluated in colon and breast cancer cell lines. The analogues showed a similar but reduced activity compared to 1,25(OH)2D3. Analogue 3 was more potent than analogue 2, and in some assays it exhibited potency similar to that of the natural ligand. © 2011 American Chemical Society.We thank the Spanish Ministry of Education and Science (Projects SAF2007-67205 and SAF2010-15291) for financial support. M.A.R. thanks the Spanish Ministry of Education and Science for an FPU fellowship.Peer Reviewe

Synthesis and biological evaluation of 1α,25-dihydroxyvitamin D 3 analogues with a long side chain at C12 and short C17 side chains

Structure-guided optimization was used to design new analogues of 1α,25-dihydroxyvitamin D3 bearing the main side chain at C12 and a shorter second hydroxylated chain at C17. The new compounds 5a–c were efficiently synthesized from ketone 9 (which is readily accessible from the Inhoffen–Lythgoe diol) with overall yields of 15%, 6%, and 3% for 5a, 5b, and 5c, respectively. The triene system was introduced by the Pd-catalyzed tandem cyclization–Suzuki coupling method. The new analogues were assayed against human colon and breast cancer cell lines and in mice. All new vitamin D3 analogues bound less strongly to the VDR than 1α,25-dihydroxyvitamin D3 but had similar antiproliferative, pro-differentiating, and transcriptional activity as the native hormone. In vivo, the three analogues had markedly low calcemic effects. © 2012 American Chemical Society.We thank the Spanish Ministry of Education and Innovation (SAF2007-67205 and SAF2010-15291 to A. Mouriño, SAF2010-18302 to A. Muñoz, and SAF2009-07631 to RPF) for financial support.Peer Reviewe

Synthesis and Biological Evaluation of 1α,25-Dihydroxyvitamin D₃ Analogues with a Long Side Chain at C12 and Short C17 Side Chains

Structure-guided optimization was used to design new analogues of 1α,25-dihydroxyvitamin D₃ bearing the main side chain at C12 and a shorter second hydroxylated chain at C17. The new compounds <b>5a</b>–<b>c</b> were efficiently synthesized from ketone <b>9</b> (which is readily accessible from the Inhoffen–Lythgoe diol) with overall yields of 15%, 6%, and 3% for <b>5a</b>, <b>5b</b>, and <b>5c</b>, respectively. The triene system was introduced by the Pd-catalyzed tandem cyclization–Suzuki coupling method. The new analogues were assayed against human colon and breast cancer cell lines and in mice. All new vitamin D₃ analogues bound less strongly to the VDR than 1α,25-dihydroxyvitamin D₃ but had similar antiproliferative, pro-differentiating, and transcriptional activity as the native hormone. In vivo, the three analogues had markedly low calcemic effects