Search results for "End-group"

Polymerizable ring-shaped molecules containing aspartic acid: synthesis and free radical polymerization of a macrocycle derived from (N'-methacryloyl…

1999

A novel polymerizable macrocycle, 6, was prepared using high dilution techniques. Starting from N-(N'-methacryloyl-11-aminoundecanoyl)-L-aspartic acid dimethyl ester (2), N-(N'methacryloyl-11-aminoundecanoyl)-α,β-bis( 4,9-dioxadodecane-1,12-diamine)-L-aspartic acid amide (4) was obtained via amino-lysis with the bifunctional amine 4,9-dioxadodecane-1,12-diamine (3) in high excess. Addition of the free amino groups to toluene-2,4-diisocyanate (5) under high dilution provided macrocycle 6. The existence and purity of 6 were confirmed by mass spectrometry, NMR and IR spectroscopy, and HPLC. The methacrylic function was used to build up oligomers by free radical polymerization, using AIBN as an…

Modular Construction of Neutral and Anionic Carboranyl-Containing Carbosilane-Based Dendrimers

2007

A modular construction of new carbosilane dendrimers, which contain four and eight peripheral carborane derivatives and propyl linkages between the C cluster and the Si atoms, has been developed using different methodologies. Regiospecific hydrosilylation of 1-C 6 H 5 -2-(CH 2 CH=CH 2 )-1,2-closo-C 2 B 10 H 10 (1) and 1-CH 3 -2-(CH 2 CH=CH 2 )-1,2-closo-C 2 B 10 H 10 (2) offers an efficient route to molecular precursors and building blocks that can provide both divergent and convergent strategies for dendritic growth. First generations of neutral carboranyl-containing dendrimers were constructed by two approaches: (a) a divergent approach via hydrosilylation of 1 and 2 with the first genera…

Synthesis and Sequential Deprotection of Triblock Copolypept(o)ides Using Orthogonal Protective Group Chemistry

2014

The synthesis of triblock copolymers based on polysarcosine, poly-N-ε-t-butyloxycarbonyl-l-lysine, and poly-N-ε-t-trifluoroacetyl-l-lysine by ring-opening polymerization of the corresponding α-amino acid N-carboxyanhydrides (NCAs) is described. For the synthesis of N-ε-t-butyloxycarbonyl-l-lysine (lysine(Boc)) NCAs, an acid-free method using trimethylsilylchloride/triethylamine as hydrochloric acid (HCl) scavengers is presented. This approach enables the synthesis of lysine(Boc) NCA of high purity (melting point 138.3 °C) in high yields. For triblock copolypept(o)ides, the degree of polymerization (Xn ) of the polysarcosine block is varied between 200 and 600; poly-N-ε-t-butyloxycarbonyl-l-…

in vitro biological evaluation of folate-functionalized block copolymer micelles for selective anti-cancer drug delivery.

2008

The main objective of this study was to evaluate the ability of folic acid-functionalized diblock copolymer micelles to improve the delivery and uptake of two poorly water-soluble anti-tumor drugs, tamoxifen and paclitaxel, to cancer cells through folate receptor targeting. The diblock copolymer used in this study comprised a hydrophilic poly[2-(methacryloyloxy)ethyl phosphorylcholine] (MPC) block, carrying at the chain end the folate targeting moiety, and a pH-sensitive hydrophobic poly[2-(diisopropylamino)ethyl methacrylate] (DPA) block (FA-MPC-DPA). The drug-loading capacities of tamoxifen- and paclitaxel-loaded micelles were determined by high performance liquid chromatography and the m…

Spherulite formation in a ?noncrystalline? two-dimensional hydrogen-bond assembly

1996

4-Urazoyl benzoic acid groups 1 are attached as terminal end group to an oligoisobutene. According to wide-angle X-ray scattering the material is amorphous. Differential scanning calorimetry, small-angle X-ray scattering, transmission electron microscopy, and polarizing microscopy show that the polar head groups form ordered two-dimensional assemblies which organize into spherulites. Temperature-dependent SAXS measurements and the d.s.c. analysis give a close insight into the order-disorder (“melting”) process of the two-dimensional clusters which form macroscopic spherulites. The order-disorder transition of the clusters is closely related to the dynamics and order of the polyisobutene cha…

Synthesis of Novel Folic Acid-Functionalized Biocompatible Block Copolymers by Atom Transfer Radical Polymerization for Gene Delivery and Encapsulati…

2005

Two synthetic routes to folic acid (FA)-functionalized diblock copolymers based on 2-(methacryloyloxy)- ethyl phosphorylcholine [MPC] and either 2-(dimethylamino)ethyl methacrylate [DMA] or 2-(diisopropylamino) ethyl methacrylate [DPA] were explored. The most successful route involved atom transfer radical polymerization (ATRP) of MPC followed by the tertiary amine methacrylate using a 9-fluorenylmethyl chloroformate (Fmoc)-protected ATRP initiator. Deprotection of the Fmoc groups produced terminal primary amine groups, which were conjugated with FA to produce two series of novel FA-functionalized biocompatible block copolymers. Nonfunctionalized MPC-DMA diblock copolymers have been previou…

Effect of catalyst composition on chain-end-group of polyethylene produced by salen-type complexes of titanium, zirconium, and vanadium

2010

Dibenzocycloheptatriene as end-group of Thiele and tetrabenzo-Chichibabin hydrocarbons

2020

The authors are grateful for the financial support from: MICIU/FEDER/AEI, Spain (PG2018-101181-B-I00, PGC2018-095808B-I00, MAT2016-80826-R, FIP-2018-HECTIC-PTM, Prometeo2019/076 and the "Severo Ochoa" Programme for Centres of Excellence in R & D; SEV-2015-0496), the European Research Council (ERC) (677023), DGR (Catalunya) (2017-SGR-918), and SNSF (Switzerland, TS., PZ00P2_174175). We thank the CSIRC-Alhambra and SciCore (Basel, Switzerland) for supercomputing facilities and the Servei de RMN, UAB, for instrument time.

UCST-type behavior of poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) in aliphatic alcohols: solvent, co-solvent, molecular weight, a…

2011

Poly[oligo(ethylene glycol) methyl ether methacrylate] (POEGMA) is shown to possess insoluble–soluble transitions (UCST-type phase behavior) in a large variety of aliphatic alcohols. Samples of different molecular weights ranging from 5 kg mol−1 to 23 kg mol−1 prepared by the RAFT process and featuring different end groups at each end were analyzed by cloud point measurements. Transitions occurred sharply and were fully reversible. The UCST was found to increase with an increasing molecular weight. Hydrophobic (alkyl chain) end groups were found to lower the critical temperature in isopropanol, while rigid aromatic end groups raised the transition temperature. In ternary mixtures of isoprop…

Two dimensional self-assembly of bis-acylureas having various functional end groups.

2011

We present the synthesis and morphology study of thirteen bis-acylurea molecules with various functional end groups. The bis-acylureas have two acylurea groups, -NH-CO-NH-CO-, divided by a pentamethylene spacer, -(CH(2))(5)-, and two symmetric functional end groups, such as, aliphatic, benzyl, mono- and bi-thiophenyl, sulfur-containing, and propargyl (HC[triple bond]CCH(2)-) moieties. The bis-acylureas were synthesized by the coupling reactions of ureas with pimeloyl chloride or pimelic acid. Upon cooling from hot isotropic solutions, the bis-acylureas spontaneously form supermolecules. In the cases of aliphatic, benzyl, mono- and bi-thiophenyl functional groups, two dimensional supramolecu…