No description available.

Yes / A continuous, scalable, and solvent‐free method for the synthesis of various naphthalic imides and perylene diimides (PDIs) using twin‐screw extrusion (TSE) is reported. Using TSE, naphthalic imides were obtained quantitatively without the need for excess amine reactant or product purification. With good functional‐group tolerance, alkyl and benzyl amine derived PDIs (incl. commercial dyes) were obtained in 50–99 % yield. Use of K2CO3, enabled synthesis of more difficult aniline‐derived PDIs. Furthermore, an automated continuous TSE process for Pigments Black 31 and 32 is demonstrated, with a throughput rate of about 1500 g day−1, corresponding to a space time yield of about 30×103 kg m−3 day−1, which is 1–2 orders of magnitude greater than for solvent‐based batch methods. These methods provide substantial waste reductions and improved efficiency compared to conventional solvent‐based methods. / Engineering and Physical Sciences Research Council. Grant Numbers: EP/L019655/1, IAA1718-04-1117

Helicenes, a class of polycyclic aromatic hydrocarbons (PAHs), are characterized by their twisted skeletons formed through ortho-annulated aromatic rings, leading to axial chirality and remarkable chiroptical properties. These features make helicenes promising candidates for advanced applications, including chiroptical nonlinear optics, asymmetric catalysis, and chiral switches. Perylene diimide (PDI), an electron-deficient PAH, is known for its exceptional optoelectronic properties and stability. Incorporating PDI units into helicene structures has emerged as an effective strategy for developing non-planar electron acceptors and molecules with enhanced chiroptical properties, making PDI-helicenes valuable for organic electronics and related fields.This thesis investigates the synthesis and chiroptical properties of PDI-[4]helicenes, presenting a method for controlling the dynamic axial chirality in PDI-based twistacenes. Chiral substituents at the imide position induce helicity within the structure, enabling the remote modulation of flexible [4] helicene subunits. Additionally, a chiral molecular redox switch, chPDI[2], derived from PDI-based twistacenes, is introduced. This material demonstrates reversible multistate chiroptical switching across a broad wavelength range, including ultraviolet, visible, and near-infrared regions. Upon reduction, chPDI[2] shows a significant enhancement in its circular dichroic response, making it a promising candidate for chiroptical switching applications. Finally, we explore chiral graphene nanoribbons (chGNRs) with acene-based cores, demonstrating helicity control in extended conjugated systems. The longest chGNR[40] exhibits one of the highest recorded chiroptical responses for organic molecules in the visible spectrum, offering new opportunities for chiral optoelectronics and molecular devices.

Le stockage de l'énergie est l'un des enjeux les plus cruciaux du 21e siècle. Le développement de matériaux abordables qui possèdent une grande densité d'énergie et qui affichent une grande stabilité est recherché. Une demande croissante venant du domaine de l'électronique portative fait pression sur la recherche de matériaux toujours plus performants. L'émergence des ordinateurs et téléphones portatifs ainsi que des véhicules électriques est la pièce maitresse de cette révolution. Par ailleurs, le stockage de l'énergie dans des batteries géantes, mais stationnaires, permettra au cours des prochaines années de pallier à la réalité de production d'énergie fluctuante du solaire et de l'éolien au cours d'une journée. La batterie Li-ion est présentement la technologie la plus mature pour mener à ce type de réalisation. L'atome de lithium est pourvu d'une petite masse molaire et l'ion lithium possède un petit rayon ionique. Utilisé à l'anode, le lithium permet d'y avoir une grande densité d'énergie, puis une faible résistance ionique dans l'électrolyte une fois oxydé. Par contre, les batteries Li-ion d'aujourd'hui reposent sur des matériaux de cathode dispendieux comme le cobalt, le nickel et le manganèse, dont l'exploitation soulève de grandes questions environnementales et éthiques. Avec une demande croissante pour des batteries de haute performance, des matériaux de cathode abordables, renouvelables et avec un impact environnemental faible doivent être développés. Dans ce contexte, les molécules organiques qui ont une activité redox ont attiré l'attention avec un faible cout de production, une faible toxicité et une abondance naturelle élevée. Parmi les différents groupements fonctionnels démontrant une activité rédox, les groupements carbonylés se démarquent par leur grande diversité, et leur stabilité à l'état réduit. Les matériaux redox typiques contenant des carbonyles sont les quinones, les 1,2-diones et les imides qui reposent sur un mécanisme d'énolisation lors du processus de réduction. La principale limitation que présentent ces molécules est la dissolution dans l'électrolyte. La formation d'un sel organique ou l'incorporation de la molécule électroactive au sein d'un polymère inerte sont des stratégies qui ont été apportées pour pallier à ce problème. La versatilité des molécules possédant des fonctions imides rend possible l'étude de plusieurs polymères π-conjugués qui ont l'avantage de pouvoir conduire davantage les charges injectées. Dans le cadre de ces travaux de doctorat, l'objectif général était de synthétiser de nouveaux polymères π-conjugués contenant des fonctions imides et d'analyser leurs performances en tant que matériau actif de cathode en batterie Li-ion. Les molécules qui ont été étudiées sont le maléimide, le pyromellitique diimide et le pyrène diimide. Des polymères π-conjugués ont été synthétisés avec ces unités en utilisant les techniques d'Ullmann, de Stille, de Suzuki ou d'arylation directe.

by Chan Hoi Shan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2000. / Includes bibliographical references (leaves 111-119). / Abstracts in English and Chinese. / Acknowledgement --- p.iii / Abbreviation --- p.iv / List of Compounds --- p.vi / Abstract --- p.vii / Abstract (Chinese) --- p.ix / Chapter Chapter 1. --- Introduction / Chapter 1.1 --- Lanthanide-Amine Compounds --- p.1 / Chapter 1.2 --- Lanthanide-Amide Compounds --- p.3 / Chapter 1.3 --- Lanthanide-Imide Compounds --- p.11 / Chapter 1.4 --- Some Applications of Lanthanide-Amide Compounds in Organic Synthesis --- p.15 / Chapter 1.5 --- Aims --- p.19 / Chapter Chapter 2. --- Synthesis and Structural Characterization of Anionic and Neutral Dichlorolanthanocene Compounds / Chapter 2.1 --- Synthesis --- p.20 / Chapter 2.2 --- Structural Characterization --- p.22 / Chapter 2.3 --- Conclusion --- p.23 / Chapter Chapter 3. --- Synthesis and Structural Characterization of Amido-Lanthanide Compounds / Chapter 3.1 --- Synthesis and Structural Characterization of Yb(NHAr)3(THF)n --- p.26 / Chapter 3.2 --- "Synthesis and Structural Characterization of Yb(NHC6H3iPr2- 2,6)4Na(THF)" --- p.38 / Chapter 3.3 --- "Synthesis and Structural Characterization of Yb(Cp"")(NHAr)2(L)" --- p.45 / Chapter 3.4 --- "Synthesis and Structural Characterization of Yb(Cp"")(NHC6H3iPr2- 2,6)3M(L)" --- p.54 / Chapter 3.5 --- Synthesis and Structural Characterization of Yb(NHAr)3(NH2Ar)(L) --- p.74 / Chapter 3.6 --- Conclusion --- p.76 / Chapter Chapter 4. --- Synthesis and Structural Characterization of Imido-Lanthanide Compounds / Chapter 4.1 --- Synthesis --- p.81 / Chapter 4.2 --- Structural Characterization --- p.82 / Chapter 4.3 --- Conclusion --- p.85 / Chapter Chapter 5. --- Summary and Remarks / Chapter 5.1 --- Summary --- p.96 / Chapter 5.2 --- Remarks --- p.97 / Chapter Chapter 6. --- Experimental Section --- p.98 / References --- p.111 / Appendix --- p.120

Orientador: Prof. Dr. Sergio Brochsztain / Dissertação (mestrado) - Universidade Federal do ABC. Programa de Pós-Graduação em Energia, 2016. / O presente trabalho visa à utilização de materiais mesoporosos funcionalizados com imidas aromáticas em algumas importantes aplicações do setor energético. Os materiais são constituídos de silicatos (SiO2) mesoporosos com a imida aromática 1,8-naftalimida (NI) ligada covalentemente às paredes dos poros, formando assim um composto híbrido com alto nível de organização. A primeira aplicação destes materiais está relacionada à captação de luz e transferência de energia entre cromóforos localizados no interior destas sílicas. Para isto, o cromóforo doador de energia foi a NI e como aceptor de energia foi a N, N- bis(2,6-dimetilfenil)¿3,4,9,10- tetracarboxilperilenodiimida (DMPDI). Através desta transferência de energia foi possível ajustar a cor de emissão de fluorescência, resultando em emissão branca, sendo interessante para aplicações em diodos emissores de luz (LEDs). Uma segunda utilização dos materiais mesoporosos realizada no presente trabalho esta relacionada à indústria do petróleo e consiste na degradação de asfaltenos através da fotocatálise heterogênea. Neste sistema, as sílicas mesoporosas funcionalizadas com a imida aromática NI foram utilizadas como compostos fotocatalisadores. Para isso, foi avaliado em um primeiro momento o desempenho destes materiais em um sistema de fotocatálise padrão constituído pelo corante azul de metileno (AM) para a subsequente aplicação na degradação dos asfaltenos. Os materiais se mostraram satisfatórios como fotocatalisadores heterogêneos, promovendo a mineralização completa do AM em cerca de 5 horas quando o sistema era irradiado com lâmpada de mercúrio. Testes preliminares mostraram que os materiais foram também efetivos na degradação de asfaltenos. / The present study has as a goal the use of mesoporous materials modified with aromatic imides for applications in the energy field. The materials consist of mesoporous silicas with 1,8-naphthalimides (NI) covalently bound to the inner pore walls. The first application tested was the potential as light harvesting materials. For this purpose, energy transfer between different chromophores within the pores was studied. For these studies, NI was used as the energy donor and N,N'-bis(2,6-dimethylphenyl)¿3,4,9,10-tetracarboxyperylenediimide (DMPDI) as the energy acceptor. It was possible to tune the color of the emission, including white emission, by adjusting the relative amount of the two imides within the pores, showing that the materials have potential applications for the construction of LEDs. A second application that was tested was the use of the mesoporous materials as photocatalysts for the degradation of petroleum asphaltenes. For this purpose, the system was initially tested with methylene blue (MB), a typical pollutant from the textile industry. Complete mineralization of MB was observed after 5 hours of irradiation with a mercury lamp, in the presence of the mesoporous materials modified with NI. Initial tests showed that the materials were also effective in the photodegradation of the asphaltenes.

The work in this thesis relates to the preparation and structural and electrical characterisation of calcium and strontium hydrides, imides and nitride hydrides. Conventional solid state methods in controlled atmospheres were used to synthesise these materials. High temperature neutron diffraction, thermal analysis and conductivity studies performed on calcium and strontium hydride suggest an order – disorder transition in these materials at 350 – 450°C. Disordering is believed to involve rapid exchange of hydride ions across two crystallographic sites. This manifests itself in a lowering of the activation energy for bulk hydride ion conduction. The hydride ion conduction is good in these undoped materials: σ[total]subscript = 0.01 S/cm for CaH₂ at 1000K; for SrH₂, σ[total]subscript = 0.01 S/cm at 830K. Doping of SrH₂ with NaH causes a significant increase in the low temperature conductivity, due to presence of extrinsic defects. The high temperature conductivity is negatively affected by NaH doping. Calcium nitride hydride (Ca₂NH) was obtained as a single phase material by reacting either calcium metal or calcium hydride (CaH₂) in an argon atmosphere containing 5 – 7% H₂ and 1 – 7% N₂. Imide ions substituting for hydride and nitride ions constitute a major chemical defect in this material. Long range ordering of the nitride and hydride ions occurs, giving rise to a double cubic crystal symmetry. This order breaks down at 600 – 650°C. Applying the same reaction conditions to strontium metal results in a mixed phase of strontium nitride hydride and imide. No long range order in the nitride hydride phase could be observed. Doping Ca₂NH with lithium hydride (LiH) causes the appearance of a second calcium imide phase, whereas doping with sodium hydride (NaH) increases the amount of imide ions as a defect in the nitride hydride structure, thereby decreasing the long range ordering of nitride and hydride ions.

Orientador: Prof. Dr. José Fernando Queiruga Rey / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2015. / Neste trabalho foram construídos filmes finos automontados a base da imida aromática N,N¿-(2-fosfonoetil)-3,4,9,10-perilenodiimida (PPDI) utilizando a técnica de fosfonato de zircônio (ZP). Os filmes foram crescidos em substratos de silício e de ITO (óxido de índio dopado com estanho). O crescimento dos filmes foi acompanhado por espectroscopia de absorção no UV-visível no caso dos filmes em ITO e refletância especular no caso dos filmes em silício. No caso de filmes em ITO foram crescidas duas séries de filmes para avaliar os efeitos do tratamento térmico. A caracterização dos filmes foi feita por microscopia de força atômica (AFM) e refletividade de raios-X (XRR). As imagens de topografia obtidas por AFM mostram que o tratamento térmico proporcionou uma cobertura mais completa no substrato de ITO. Os valores de rugosidade quadrática média (RMS) obtidos mostram que a rugosidade dos filmes aumenta inicialmente mas passa a diminuir com a deposição de mais camadas. Isto sugere que o substrato pode influenciar na rugosidade do filme até um determinado número de camadas, e após isto, as camadas de filme previamente depositadas passam a ser o efeito predominante. As curvas de refletividade de raios-X sugerem que os filmes em silício estão mais organizados do que os filmes em ITO, demonstrando a influência do substrato na organização dos filmes automontados crescidos sobre ele. / In this work were constructed self-assembled thin films based on the aromatic imide N, N '- (2-phosphonoethyl) -3,4,9,10-perylendiimide (PPDI) using zirconium phosphonate method (ZP). The films were grown on silicon and ITO (indium-tin oxide) substrates. The growth of the films was monitored by absorption spectroscopy in the UV-visible in the case of films on ITO and specular reflectance in the case of films on silicon. Two series of films were grown on ITO substrates to evaluate the effects of heat treatment. The characterization of the films was made by atomic force microscopy (AFM) and X-ray reflectivity (XRR). The AFM topography images obtained show that the heat treatment provided a more complete coverage of the ITO substrate. The mean square roughness values (RMS) obtained show that the roughness of films initially increases but decrease with deposition of further layers. This suggests that the substrate can influence the roughness of the film up to a certain number of layers, and after that, the previously deposited film layers become the predominant effect. The reflectivity curves of X-rays suggest that the silicon films are more organized than the ITO films, demonstrating the influence of substrate on the organization of self-assembled films grown on it.

Made available in DSpace on 2015-05-14T12:59:54Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1256477 bytes, checksum: f676b1f9aeaea49632e26bd31031dcf4 (MD5) Previous issue date: 2013-03-01 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Compounds derived from plants or animals have been instrumental in the discovery of anti-infective drugs, and now many synthetic antimicrobial drugs based on structural models of substances of natural origin. Several chemical compounds, natural and synthetic, have been reported as inhibitors of efflux pumps, acting as important additional tools in drug development co-formulated with appropriate antibiotics. In this study were evaluated seven N-Fenylmaleimides (NFM), gently assigned by Dr. Valdir Cechinel Filho (UNIVALI), obtained by organic synthesis. The values of the minimum inhibitory and bactericidal concentrations (MIC and MBC) of N-Fenylmaleimides (NFM), antibiotics and compounds NAB, by the broth microdilution method.Were determined the values of minimum inhibitory concentrations (MIC) of NFM, antibiotics and compounds NAB. In modulation of drug resistance, the MIC of the antibiotic compounds and NAB were determined in the presence and absence of subinibitory concentrations of NFM. Both studies were supplemented with analysis of in silico ADMET parameters. The derivatives 3,4-Cl-NFM, NFM-4-Cl and 4-CH3-NFM showed moderate antibacterial activity with MIC of up to 64 μg/mL in MSSA and MRSA strains. In the assay of modulation of drug resistance, 4-NO2-NFM reduced by up to four times the MIC of the antibiotic tetracycline and erythromycin. The 4-CH3 NFM showed the best results, with a reduction in MIC of the antibiotics tetracycline (up to 4-fold), erythromycin (16-fold), some representatives of fluoroquinolones (up to 4-fold) and compounds NAB (up to 4 times). By reducing the MIC of ethidium bromide, 4-CH3 NFM is considered in fact as a putative inhibitor of the efflux system in bacteria. In the analysis of molecular modeling, derivatives 3,4-Cl-NFM and 4-CH3-NFM, improved antibacterial and modulator compounds respectively, showed a profile with low toxic risk theoretical profile since they are promising to be used in drawing new derivatives more active and safer. The results presented here show that imidic derivatives may be used to potentiate the effect of antimicrobial agents to facilitate reintroduction of antibiotics currently ineffective for the clinical treatment of multiresistant infections. / Compostos derivados de vegetais ou animais têm sido cruciais na descoberta de drogas anti-infecciosas, e atualmente muitas drogas antimicrobianas sintéticas baseiam-se em modelos estruturais de substâncias de origem natural. Diversos compostos químicos, sintéticos e naturais, têm sido relatados como inibidores de bombas de efluxo, atuando como ferramentas adicionais importantes no desenvolvimento de fármacos co-formulados com os antibióticos apropriados. Neste trabalho foram avaliados sete N-Fenilmaleimidas (NFM), cedidas gentilmente pelo Prof. Dr. Valdir Cechinel Filho (UNIVALI), obtidas por síntese orgânica. Foram determinados os valores das concentrações inibitórias mínimas e bactericida (CIM e CBM) de N-Fenilmaleimidas, dos antibióticos e dos compostos NAB, pelo método da microdiluição em placa. Na atividade moduladora de drogas, as CIM dos antibióticos e compostos NAB foram determinadas na presença e ausência de concentrações subinibitórias das N-Fenilmaleimidas. Ambos os estudos foram complementados com análise in silico dos parâmetros ADMET. Os derivados 3,4-Cl-NFM, 4-Cl-NFM e 4-CH3-NFM mostraram atividade antibacteriana moderada, com CIM de até 64 μg/mL em cepas MSSA e MRSA. No ensaio da modulação da resistência a drogas, a 4-NO2-NFM reduziu em até 4 vezes a CIM dos antibióticos tetraciclina e eritromicina. A 4-CH3 NFM apresentou o melhor resultado, com redução da CIM dos antibióticos tetraciclina (até 4 vezes), eritromicina (até 16 vezes), alguns representantes das fluoroquinolonas (até 4 vezes) e compostos NAB (até 4 vezes). Ao reduzir a CIM do brometo de etídio, a 4-CH3 NFM é considerada de fato como inibidor putativo do sistema de efluxo em bactéria. Na análise da modelagem molecular, os derivados 3,4-Cl-NFM e 4-CH3 NFM, os quais apresentaram melhor atividade antibacteriana e moduladora da resistencia, respectivamente, mostraram um perfil com baixo risco tóxico teórico, resultado promissor para serem utilizados no desenho de novos derivados mais ativos e mais seguros. Os resultados aqui apresentaram mostram que derivados imídicos podem ser utilizados para potenciar o efeito de agentes antimicrobianos, de modo a facilitar a reintrodução de antibióticos atualmente ineficazes para o tratamento clínico de infecções multirresistentes.

The research work reported in this thesis is focused on the chiral analysis, quantification of enantiomeric composition, assignment of absolute configuration of molecules with chosen functional groups. The weak intra-molecular hydrogen bonding interactions are detected by exploiting several multinuclear and multi-dimensional techniques. Pulse sequences have been designed to manipulate the spin dynamics to derive specific information from the complex NMR spectra encountered in diverse situations. Broadly, the thesis can be classified in to three sections. The section I containing two chapters reports the introduction of new chiral auxiliaries and protocols developed for enantiomeric discrimination, measurement of enantiomeric contents, assignment of absolute configuration for molecules possessing specific functional groups using chiral solvating and derivatizing agents. The section II, reports NMR experimental evidence for the observation of the rare type of intramolecular hydrogen bonds involving organic fluorine in biologically important organic molecules, that are corroborated by extensive DFT based theoretical calculations. The section II also discusses the H/D exchange mechanism as a tool for quantification of HB strengths in organic building blocks. The section III reports the two different novel NMR methodologies designed for deriving information on the scalar interaction strengths in an orchestrated manner. The designed sequences are able to completely eradicate the axial peaks, prevents the evolution of unwanted couplings and also yields ultrahigh resolution in the direct dimension, permitting the accurate measurement of scalar couplings for a particular spin. The brief summary about each chapter is given below. Chapter 1 provides a general introduction to one and two dimensional NMR spectroscopy. The pedagogical approach has been followed to discuss the conceptual understanding of spin physics and the NMR spectral parameters. The basic introduction to chirality, existing approaches in the literature for discrimination of enantiomers and the assignment of absolute configuration of molecules with chosen functional groups and their limitations are briefly discussed. The brief introduction to hydrogen bond, experimental methods to obtain the qualitative information about the strengths of hydrogen bonds, and the theoretical approaches employed in the thesis to corroborate the NMR experimental findings have been provided. The mechanism of H/D exchange, the utilization of exchange rates to derive strengths of intra-molecular hydrogen bond in small molecules have also been discussed. This chapter builds the bridge for the rest of the chapters. Each of these topics are discussed at length in the corresponding chapters. Part I: NMR Chiral Analysis: Novel Protocols Chapter 2 discusses a simple mix and shake method for testing the enantiopurity of primary, secondary and tertiary chiral amines and their derivatives, amino alcohols. The protocol involves the in-situ formation of chiral ammonium borate salt from a mixture of C2 symmetric chiral BINOL, trialkoxyborane and chiral amines. The proposed concept has been convincingly demonstrated for the visualization of enantiomers of a large number of chiral and pro-chiral amines and amino alcohols. The protocol also permits the precise measurement of enantiomeric composition. The significant advantage of the protocol is that it can be performed directly in the NMR tube, without any physical purification. The structure of the borate complex responsible for the enantiodifferentiation of amines has also been established by employing multinuclear NMR techniques and DFT calculations. From DOSY and 11B NMR experiments it has been ascertained that there are only two possible complexes or entities which are responsible for differentiating enantiomers. From the combined utility of DFT calculations and the 11B NMR chemical shifts, the structure of the borate complex has been determined to be an amine-coordinated complex with the N atom of the amine. Chapter 3 discusses a simple chiral derivatizing protocol involving the coupling of 2-formylphenylboronic acid and an optically pure [1,1-binaphthalene]-2,2-diamine for the rapid and accurate determination of the enantiopurity of hydroxy acids and their derivatives, possessing one or two optically active centers. It is established that this protocol is not only rapid method for discrimination of enantiomers but also highly effective for assigning the absolute configuration of various chiral hydroxy acids and their derivatives. The developed protocol involves the coupling of 2-formylphenylboronic acid with (R)-[1,1-binaphthalene]-2,2-diamine, and 2-formylphenylboronic acid with (S)-[1,1-binaphthalene]-2,2-diamine as chiral derivatizing agents. The absence of aliphatic peaks from the derivatizing agent, large chemical shift separation between the discriminated peaks of diastereomers, and the systematic change in the direction of displacement of peaks for an enantiomer in a particular diastereomeric complex, permitted the unambiguous assignment of absolute configuration. Part II : Rare Type of Intramolecular Hydrogen Bonding In chapter 4 The rare occurrence of intramolecular hydrogen bonds of the type N–H˖˖˖F–C, in the derivatives of imides and hydrazides in a low polarity solvent, is convincingly established by employing multi-dimensional and multinuclear solution state NMR experiments. The observation of 1hJFH, 2hJFN, and 2hJFF of significant strengths, where the spin polarization is transmitted through space among the interacting NMR active nuclei, provided strong and conclusive evidence for the existence of intra-molecular hydrogen bonds. Solvent induced perturbations and the variable temperature NMR experiments unambiguously supported the presence of intramolecular hydrogen bond. The two dimensional HOESY and 15N–1H HSQC experiments reveals the existence of multiple conformers in some of the investigated molecules. The 1H DOSY experimental results discarded any possibility of self or cross-dimerization of the molecules. The results of DFT based calculations, viz., Quantum Theory of Atoms In Molecules (QTAIM) and Non Covalent Interaction (NCI), are in close agreement with the NMR experimental findings. In chapter 5 the rates of hydrogen/deuterium (H/D) exchange determined by 1H NMR spectra have been utilized to derive the strength of hydrogen bonds and to monitor the electronic effects in the site-specific halogen substituted benzamides and anilines. The theoretical fitting of the time dependent variation in the integral areas of 1H NMR resonances to the first order decay function permitted the determination of H/D exchange rate constants (k) and their precise half-lives (t1/2) with high degree of reproducibility. The comparative study also permitted the determination of relative strengths of hydrogen bonds and the contribution from electronic effects on the H/D exchange rates. Part III: Novel NMR Methodologies for the Precise Measurement of 1H-1H Couplings Chapter 6 describes two novel NMR methodologies developed for the precise measurement of 1H-1H couplings. Poor chemical shift dispersion and the pairwise interaction among the entire coupled network of protons results in the severely complex and overcrowded one dimensional 1H NMR spectra, hampering both the resonance assignments and the accurate determination of nJHH. The available two-dimensional selective refocusing (SERF) based experiments suffer from the evolution of magnetization from uncoupled protons as intense uninformative axial peaks. This creates ambiguity in the identification of peaks belonging to the coupled partners of a selectively excited proton, hindering the extraction of their interaction strengths. This challenge has been circumvented by designing two novel experimental technique, cited as “Clean-G-SERF” and “PS-Clean-G-SERF”. The Clean-G-SERF technique completely eradicates the axial peaks and suppresses the evolution of unwanted couplings while retaining only the couplings to the selectively excited proton. The method permits the accurate determination of spin-spin couplings even from a complex proton NMR spectrum in an orchestrated manner. The PS-Clean-G-SERF technique has been designed for the complete elimination of axial peaks and undesired couplings, with a blend of ultra-high resolution achieved by real time broad band homonuclear decoupling has been discussed in this chapter. The spin dynamics involved in both these pulse sequences have been discussed. The diverse applications of both these novel experiments have been demonstrated.