174877-79-3Relevant academic research and scientific papers
Effect of the bulkiness of the end functional amide groups on the optical, gelation, and morphological properties of oligo(p-phenylenevinylene) π-gelators
Babu, Sukumaran Santhosh,Praveen, Vakayil K.,Kartha, Kalathil K.,Mahesh, Sankarapillai,Ajayaghosh, Ayyappanpillai
, p. 1830 - 1840 (2014/07/08)
Herein, we describe the role of end functional groups in the self-assembly of amide-functionalized oligo(p-phenylenevinylene) (OPV) gelators with different end-groups. The interplay between hydrogen-bonding and π-stacking interactions was controlled by the bulkiness of the end functional groups, thereby resulting in aggregates of different types, which led to the gelation of a wide range of solvents. The variable-temperature UV/Vis absorption and fluorescence spectroscopic features of gelators with small end-groups revealed the formation of 1D H-type aggregates in CHCl3. However, under fast cooling in toluene, 1D H-type aggregates were formed, whereas slow cooling resulted in 2D H-type aggregates. OPV amide with bulky dendritic end-group formed hydrogen-bonded random aggregates in toluene and a morphology transition from vesicles into fibrous aggregates was observed in THF. Interestingly, the presence of bulky end-group enhanced fluorescence in the xerogel state and aggregation in polar solvents. The difference between the aggregation properties of OPV amides with small and bulky end-groups allowed the preparation of self-assembled structures with distinct morphological and optical features. Buying in bulk: OPV amides with small end-groups self-assemble into 2D/1D aggregates in toluene and 1D aggregates in CHCl3. Bulky end-groups impede fluorescence quenching in the self-assembled state by blocking π-stacking and facilitate morphological transition in THF.
Luminescent micro and nanogel formation from AB3 type poly(aryl ether) dendron derivatives without conventional multi-interactive gelation motifs
Rajamalli,Prasad, Edamana
, p. 1541 - 1548 (2011/09/20)
We report the synthesis, gelation and photophysical properties of luminescent AB3 type poly(aryl ether) dendron derivatives in the absence of conventional multi-interactive gelation motifs. The gelation process is controlled through employing partial polar solvent milieu, which significantly enhances the propensity of π-π interaction between the aryl units present in the system. The self-assembly leads to unprecedented gelation through entrapping solvent molecules in the fibrillar arrangement of poly(aryl ether) units. The strategy was further utilized to prepare an excimer based photoluminescent gel through incorporating anthracene units in the dendrons. The close proximity between the anthracene units in the gel renders the formation of anthracene excimers at room temperature, resulting in the emission of bright green light from the gel, upon UV excitation. The study suggests that the size and packing of the self-assembled fibre can be controlled by the generation and functional groups present in the dendron. Furthermore, the strategy envisages an easy approach to generate fluorescent Low Molecular-mass Organic Gelator (LMOG) through incorporating poly cyclic aromatic hydrocarbon units to the poly(aryl ether) dendrons, since the self-assembly is largely guided by π-π interactions. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique.
Synthesis of dendronized polymers through bergman cyclization of enediyne-containing Frechet-type dendrimers
Ma, Jianguo,Ma, Xiaowei,Deng, Sheng,Li, Fei,Hu, Aiguo
, p. 1368 - 1375 (2012/02/14)
In this article, dendronized polymers with rigid backbones were synthesized from enediyne-containing Frechet-type dendrimers. Two generations of dendrimers were conically incorporated with 3-(2-(2-(trimethylsilyl)ethynyl)phenyl)prop-2- yn-1-ol. The trimethylsilyl protection groups of enediyne units were subsequently removed, and two types of brush polymers with rigid conjugated backbone were prepared through Bergman cyclization polymerization at elevated temperature under vacuum. The dendronized polymers were characterized with GPC, IR, UV-vis, and NMR spectroscopy. Furthermore, the morphology of the dendronized polymer was revealed by atomic force microscopy.
Hydrogen-bonded dendronized polymers and their self-assembly in solution
Xie, Dang,Jiang, Ming,Zhang, Guangzhao,Chen, Daoyong
, p. 3346 - 3353 (2008/02/08)
Frechet-type benzyl ether dendrons of second and third generations with a carboxyl group (G2, G3) at the apex site could attach to poly(4-vinylpyridine) (PVP), forming hydrogen-bonded dendronized polymers (HB denpols) in their common solvent, chloroform. The HB denpols show unique self-assembly behavior, forming vesicles in the common solvent under ultrasonic treatment. The structure and morphology of the vesicles were characterized by dynamic light scattering (DLS), static light scattering (SLS), SEM, TEM, and AFM. The size of the vesicles decreases and the thickness of the vascular membrane increases as the molar ratio of Gx/PVP increases. The hydrogen bonding. π-π aromatic stacking of the dendrons. and the considerable difference in architecture between the dendron Gx and PVP are the main factors facilitating the assembly of the HB denpols in the common solvent.
Self-assembly of chiral depsipeptide dendrimers
Hager, Kristine,Franz, Alexander,Hirsch, Andreas
, p. 2663 - 2679 (2008/02/03)
The self-assembly of chiral depsipeptide dendrons 4, which contain a cyanuric acid building block at their focal point, with the homotritopic Hamilton receptor 1 is reported. The 1:3 compositions of the resulting chiral supramolecular dendrimers, the association constants Kn, and the cooperativity of binding expressed by Scatchard plots and the Hill coefficients nH was determined by NMR titration experiments. The most pronounced positive cooperativity was found for the complexes 1L3 with L being the second-generation dendrons 4c-e. The least stable complexes are formed with the bulky third-generation dendrons 4f-h. Similar results are obtained by the corresponding complexation of the achiral Frechet-type first- to third-generation dendrons 3 with 1. Chiroptical investigations of 1:3 complexes of 1 and 4 reveal chirality transfer from the dendron to the Hamilton receptor as demonstrated by the appearance of new CD absorption bands at 310 nm.
