Substituent effects on 1H and 13C NMR chemical shifts in α‐monosubstituted ethyl acetates: principal component analysis and 1H chemical shift calculations

Tasić, Ljubica; Abraham, Raymond J.; Rittner, Roberto

doi:10.1002/mrc.1046

Cited by 14 publications

(12 citation statements)

References 18 publications

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“…5 and in Table 2. These results are very similar to ones already observed for unsaturated and carbonylic compounds [12,14], and present the 117-compounds division in four substituent groups: (1) the neutral (Me, Et as substituents) together with parent compounds (H); (2) nitrogen derivatives (NMe 2 and NEt 2 ); (3) sulfur derivatives (SMe and SEt); and (4) oxygen derivatives (OMe and OEt). From the original set of 169 compounds, the halogen derivatives were excluded [14], and two principal components with 96.47% of variance and three variables ( Table 2) were applied in this PCA.…”

Section: Resultssupporting

confidence: 87%

“…2) and acyclic (10 and 12, Fig. 2), were more similar among each other as already expected [12]. Unsaturated compounds (7-9) presented the lack of grouping and no similarity in 13 C NMR data.…”

Section: Resultssupporting

confidence: 71%

“…The functional carbon chemical shifts used as one of the variables in this PCA (Table 1) [10][11][12][13]. According to previous analyses [14] this could be due to the probable lack of conjugation between sulfur and carbonylic oxygen.…”

Section: Resultsmentioning

confidence: 99%

“…The interactions between the Y substituent and the X functional group have been studied for years in our laboratory by NMR, IR and rotational isomerism and the differences between observed and expected chemical shifts have been attributed to various substituent effects, all of these were treated by classical regression analysis [7][8][9], and also by PCA in last decade [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

“…1) compounds which were the object of our investigations. Often, the nonadditivity of their 13 C NMR chemical shifts, manifested by variation in substituent-induced chemical shift (SCS) values, are explained as the consequence of mutual substituent interactions which modify the amount of delocalized charge by the substituent Y [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

α-Substituent effects on 13C NMR chemical shifts in some aliphatic compounds: Application of principal component analysis (PCA)

Tasić

Rittner

2009

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Section: Resultssupporting

confidence: 87%

Section: Resultssupporting

confidence: 71%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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α-Substituent effects on 13C NMR chemical shifts in some aliphatic compounds: Application of principal component analysis (PCA)

Tasić

Rittner

2009

Journal of Molecular Structure

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Synthesis and characterization of fourth generation polyester‐based dendrimers with cationic amino acids‐modified crown as promising water soluble biomedical devices

Alfei

Catena

2018

Polymers for Advanced Techs

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Dendrimers are nanostructured “architectural motifs” which fascinate researchers for their several potentiality due to well‐tailored structure, symmetric tree‐like shape, and abilities in entrapping or binding hydrophilic or hydrophobic entities such as genetic materials, drugs, and target molecules. Nowadays dendrimers inhabit the top places among the materials suitable for biomedical applications as drug delivery, gene transfection, and imaging. In this work, we report the design and realization of two versatile successful procedures to decorate a fourth generation polyester‐based dendrimer matrix with a mixture of four different amino acids. The hydrochloride dendrimers achieved after removal of protecting groups were characterized by a core‐shell structure. They harmonized a not charged hydrolysable inner matrix potentially able to accommodate hydrophobic molecules and a cationic highly hydrophilic crown conferred by biocompatible amino acids that provided very satisfactory buffer capacity and will allow easy host/guest electrostatic interactions. Their structures and peripheral composition were confirmed by NMR analysis and experimental molecular weight computed by volumetric titration, while their buffer capacity was obtained by potentiometric titrations. Because in the inner matrix, the achieved hetero dendrimers do not present the high density of positive charges typical of PAMAM, they ensure a lower level of toxicity. But thanks to the cationic periphery, as preliminary investigations still in progress have already put in evidence, they were able to entrap not water soluble molecules by electrostatic interactions, with the result to increase their water solubility in a very satisfactory or amazing way. They therefore represent two new very promising devices for biomedical applications.

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Synthesis and characterization of versatile amphiphilic dendrimers peripherally decorated with positively charged amino acids

Alfei

Catena

2018

Polymer International

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Dendrimers are nanostructured ‘architectural motifs’ with a well‐tailored polymeric structure, symmetric tree‐like shape and the presence of several functional groups and inner cavities, and are of eminent interest in many biomedical applications such as drug delivery, gene transfection and imaging. In the work reported, reliable protocols for the synthesis of polyester‐based, hydrolysable, amphiphilic polycationic dendrimers were developed. A C‐18 hydrocarbon chain provided by a biocompatible fatty acid, stearic acid, and second‐ and third‐generation dendrons based on 2,2‐bis(hydroxymethyl)propionic acid were built on 2,2‐bis(hydroxymethyl)propanol and pentaerythritol as core molecules. αN‐BOC‐ω'N‐(NO2)‐l‐arginine alone, mixed with αN,ϵN‐di‐BOC‐l‐lysine or also with N,N′‐dimethylglycine and αN‐BOC‐methylglycine were successfully bound to the prepared polyester neutral scaffolds and, after the removal of protecting groups, five cationic dendrimers were obtained. Their structure was confirmed using NMR analysis and experimental molecular weight. Their buffer capacity, comparable to that of polyethyleneimines, was optimal, high viability percentage values were obtained from cytotoxicity assays and zeta potential and mean particle size were in the desired ranges. The synthesized nanostructured compounds that harmonize a multifunctional polycationic shell, a biodegradable uncharged polyester matrix and a C‐18 hydrophobic portion helpful for an improved hydrophilic–lipophilic balance in their structure embody all the fundamental features to be suitable for biomedical applications. © 2018 Society of Chemical Industry

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Substituent effects on ¹H and ¹³C NMR chemical shifts in α‐monosubstituted ethyl acetates: principal component analysis and ¹H chemical shift calculations

Cited by 14 publications

References 18 publications

α-Substituent effects on 13C NMR chemical shifts in some aliphatic compounds: Application of principal component analysis (PCA)

α-Substituent effects on 13C NMR chemical shifts in some aliphatic compounds: Application of principal component analysis (PCA)

Synthesis and characterization of fourth generation polyester‐based dendrimers with cationic amino acids‐modified crown as promising water soluble biomedical devices

Synthesis and characterization of versatile amphiphilic dendrimers peripherally decorated with positively charged amino acids

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