80974-42-1Relevant academic research and scientific papers
Tunable Aggregation-Induced Multicolor Emission of Organic Nanoparticles by Varying the Substituent in Naphthalene Diimide
Choudhury, Pritam,Sarkar, Saheli,Das, Prasanta Kumar
, p. 14328 - 14341 (2018/11/23)
In this article, we have designed l-aspartic acid-linked naphthalene diimide (NDI)-based amphiphilic molecules having a benzyl ester group at both the terminals with varying substituents (NAB-1-5). The substituent was judiciously modified from an electron-withdrawing group (EWG) like nitrobenzene to an electron-donating group (EDG), methoxybenzene, and finally to an extended aromatic residue (naphthalene) to regulate the π-electron density at the terminal of NDI derivatives. All of the synthesized NDI derivatives were molecularly dissolved in dimethyl sulfoxide (DMSO), and with an increase in the water content within the DMSO solution, the NDI derivative starts to get self-assembled through J-aggregation at and above 40% water content. Self-assembled spherical organic nanoparticles formed in 99% water in DMSO (fw = 99%) were characterized by microscopic studies. All of the NDI derivatives showed very weak emission in the molecularly dissolved state (DMSO). Aggregation-induced emission (AIE) was observed for the NDI derivatives (except NAB-1) at the self-assembled state through excimer formation. Upon excitation at 350 nm, the emission maxima of these NDI-based AIE luminogens (AIE-gens) (NAB-2-5) get red shifted from 463 to 588 nm upon altering the substitution from EWG to EDG at the donor site. Inclusion of proper donor-acceptor moieties in the molecular backbone of the self-assembling unit can govern the AIE in combination with the intramolecular charge-transfer process. Consequently, the emission color of these AIE-gens (NAB-2-5) gets tuned from cyan blue to faint green to strong green and finally to bright orange. The tunable aggregation-induced multicolor emission was investigated by different spectroscopic techniques. These cytocompatible, multicolor-emitting fluorescent organic nanoparticles were utilized for bioimaging applications.
Designer peptide dendrimers using click reaction
Haridas,Sharma, Yogesh K.,Sahu, Srikanta,Verma, Ram P.,Sadanandan, Sandhya,Kacheshwar, Bharat G.
experimental part, p. 1873 - 1884 (2011/04/17)
We designed and synthesized various peptide dendrimers using a 1,3-dipolar cycloaddition (Click) reaction. The dendritic structures reported here include symmetrical, asymmetrical, and cationic dendrimers with triazole, cystine, aromatic, aliphatic, and Lys-Asp dipeptide cores. The high chemoselectivity of the click reaction allowed us to synthesize good yields of high-purity protected and unprotected dendritic structures. Triazole is an excellent peptide bond mimic, which remains hydrolytically stable. Dendrimer 15a and the core unit 21 gelate in a mixture of organic solvents. We also demonstrated the versatility of the design by synthesizing various carbohydrate-based dendrimers.
Chirospecific Synthesis of (1S,3R)-1-Amino-3-(hydroxymethyl)cyclopentane, Precursor for Carbocyclic Nucleoside Synthesis. Dieckmann Cyclization with an α-Amino Acid
Bergmeier, Stephen C.,Cobas, Agustin A.,Rapoport, Henry
, p. 2369 - 2376 (2007/10/02)
Carbocyclic nucleosides are important isosters of nucleosides possessing a variety of antiviral and antineoplastic activities.We report here a new method for the chirospecific synthesis of (1S,3R)-1-amino-3-(hydroxymethyl)cyclopentane.This compound is a key precursor for the synthesis of some carbocyclic nucleosides.The method involves (1) an improved synthesis of (S)-2-aminoadipic acid; (2) Dieckmann cyclization of this α-amino acid to an aminocyclopentanone; and (3) elaboration of the latter to the target (1S,3R)-1-amino-3-(hydroxymethyl)cyclopentane.The starting (S)-2-aminoadipic acid δ-methyl ester was prepared enantiomerically pure from (S)-aspartic acid in 51percent overall yield.Dieckmann condensation converted this amino acid to a (methoxycarbonyl)-cyclopentanone, and reduction of the ketone followed by elimination yielded (S)-3--1-(methoxycarbonyl)cyclopentene.Reduction of the double bond gave a mixture of the cis and trans diastereomers.This mixture was converted to a single diastereomer by epimerization and trapping of the cis isomer as (1S,4R)-2-(9-phenylfluoren-9-yl)-2-azabicycloheptan-3-one.Hydrolytic cleavage of the lactam followed by reduction gave (1S,3R)-1-amino-3-(hydroxymethyl)cyclopentane.
SYNTHESIS OF THE SERINE EQUIVALENT, (2R) AND (2S)-AMINO-3-BUTENOL DERIVATIVES. SYNTHETIC APPROACHES TO THE METAL CHELATING POLY-AMINO ACID, "ASPERGILLOMARASMINE A"
Ohfune, Yasufumi,Kurokawa, Natsuko
, p. 1071 - 1074 (2007/10/02)
Chiral synthons, equivalent to the C3 amino acid serine, were synthesized in both (2R) and (2S) form from D or L-methionine respectively; Utilization of this synthon in the construction of metal chelating poly-amino acid aspergillomarasmine A skeleton is presented.
