The Development of New Classes of Enantioselective Hydrogen Bond Donor Catalysts for Organic Synthesis Based upon Werner Complexes

In this dissertation, the development of highly effective, chiral monofunctional and bifunctional hydrogen bond donor catalysts based on cobalt(III) Werner complexes and their applications in enantioselective catalysis have been described. Furthermore, a protocol was developed to extend this chemistry into the fluorous media. Section 1 provides an overview of the hydrogen bond mediated organocatalysis and the scope of Werner complexes as hydrogen bond donors. Section 2 describes the fundamental stereochemical features of the trication [Co(en)3]3+ (en = ethylenediamine). Interactions between the trication, counter anions, and solvates are analyzed and a systematic nomenclature is developed. Section 3 provides highly diastereoselective syntheses of variety of diastereopure salts Λ- and Δ-[Co((S,S)-NHv2CHArCHArNHv2)v3]^3+ 2X–X'– (Ar = Cv6Hv5, vCv6Hv4n-Bu, 4- Cv6Hv4Cl, 4-Cv6Hv4CFv3, 4-Cv6Hv4OCHv3, ɑ-naphthyl, ß-naphthyl, 2-Cv6Hv4OBn; X/X' = Cl/BArvf (BArvf = B(3,5-Cv6Hv3(CFv3)v2)v4), PFv6/BArf, BF4/BArf, PhBF3/BArf, Cl/BArf20 (BArvf20 = B(Cv6F5)4), BArf/BArf, BArf20/BArvf20, BFv4/BFv4, PFv6/PFv6) and probes their properties. Sections 4 and 5 provide detail applications of the lipophilic salts of Λ- or Δ- [Co((S,S)-dpen)v3]^3+ ((S,S)-dpen = (S,S)-1,2-diphenylethylenediamine) in enantioselective addition reactions. Under optimized conditions, Λ-[Co((S,S)-dpen)v3]^3+ 3BFv4– catalyzes the Michael addition of dialkyl malonate to nitroalkenes in the presence of Et3N, affording adducts in up to 98% yields and 96% ee. Interestingly, Δ-[Co((S,S)- dpen)v3]^3+ 2Cl–BArvf20– is superior for the additions of cyclic ß-ketoesters to azodicarboylate diesters (up to 99% yields and >99% ee). Section 6 describes efficient syntheses of tris(hydrochloric acid) salts of chiral triamines Hv2NCH((CHv2)nNMe2)CHv2NHv2 (n = 1-4) from commercial starting materials in overall yields of 38-18%. Section 7 highlights syntheses of bifunctional catalysts and their applications in additions of dialkyl malonates to nitroalkenes. Racemic [Co(en)v2Ov2CO]^+ Cl^– and enantiopure (S)-[Hv3NCH((CH2)nNHMe2)CHv2NHv3]^3+ 3Cl^– (n = 1-4) are combined (water/ charcoal/100 °C) to give [Co(en)v2((S)-Hv2NCH((CHv2)vnNMev2H)CHv2NHv2)]4^+ 4Cl^–. The cobalt diastereomers (Δ/Δ)are separated via chiral Sephadex columns. Reactions with NaOH and Na^+ BArvf^– give the catalysts Λ- or Δ-[Co(en)v2((S)-Hv2NCH- ((CHv2)nNMev2)CHv2NHv2)]^3+ 3BArvf^–. Under optimized condition, Λ-[Co(en)v2((S)- Hv2NCH((CHv2)v3NMev2)CHv2NHv2)]^3+ 3BArvf^– gives addition products up to 98% yield and 99% ee. Section 8 describes an optimized procedure for the synthesis of highly fluorous Na^+ B(3,5-Cv6Hv3((CFv2)5CFv3)v2)v4– and its application in transporting polycations into fluorous media

Aortic aneurysm and non-Hodgkin’s lymphoma in Marfan syndrome

The combination of Marfan syndrome with lymphoma is extremely rare. This report describes a case of Marfan syndrome who presented with chest discomfort and was diagnosed to have an aortic aneurysm and an additional incidental mediastinal mass that on further investigation turned out to be a diffuse large B cell lymphoma. We have suggested a hypothesis which can explain the occurrence of lymphoma in Marfan syndrome

The Development of New Classes of Enantioselective Hydrogen Bond Donor Catalysts for Organic Synthesis Based upon Werner Complexes

In this dissertation, the development of highly effective, chiral monofunctional and bifunctional hydrogen bond donor catalysts based on cobalt(III) Werner complexes and their applications in enantioselective catalysis have been described. Furthermore, a protocol was developed to extend this chemistry into the fluorous media. Section 1 provides an overview of the hydrogen bond mediated organocatalysis and the scope of Werner complexes as hydrogen bond donors. Section 2 describes the fundamental stereochemical features of the trication [Co(en)3]3+ (en = ethylenediamine). Interactions between the trication, counter anions, and solvates are analyzed and a systematic nomenclature is developed. Section 3 provides highly diastereoselective syntheses of variety of diastereopure salts Λ- and Δ-[Co((S,S)-NHv2CHArCHArNHv2)v3]^3+ 2X–X'– (Ar = Cv6Hv5, vCv6Hv4n-Bu, 4- Cv6Hv4Cl, 4-Cv6Hv4CFv3, 4-Cv6Hv4OCHv3, ɑ-naphthyl, ß-naphthyl, 2-Cv6Hv4OBn; X/X' = Cl/BArvf (BArvf = B(3,5-Cv6Hv3(CFv3)v2)v4), PFv6/BArf, BF4/BArf, PhBF3/BArf, Cl/BArf20 (BArvf20 = B(Cv6F5)4), BArf/BArf, BArf20/BArvf20, BFv4/BFv4, PFv6/PFv6) and probes their properties. Sections 4 and 5 provide detail applications of the lipophilic salts of Λ- or Δ- [Co((S,S)-dpen)v3]^3+ ((S,S)-dpen = (S,S)-1,2-diphenylethylenediamine) in enantioselective addition reactions. Under optimized conditions, Λ-[Co((S,S)-dpen)v3]^3+ 3BFv4– catalyzes the Michael addition of dialkyl malonate to nitroalkenes in the presence of Et3N, affording adducts in up to 98% yields and 96% ee. Interestingly, Δ-[Co((S,S)- dpen)v3]^3+ 2Cl–BArvf20– is superior for the additions of cyclic ß-ketoesters to azodicarboylate diesters (up to 99% yields and >99% ee). Section 6 describes efficient syntheses of tris(hydrochloric acid) salts of chiral triamines Hv2NCH((CHv2)nNMe2)CHv2NHv2 (n = 1-4) from commercial starting materials in overall yields of 38-18%. Section 7 highlights syntheses of bifunctional catalysts and their applications in additions of dialkyl malonates to nitroalkenes. Racemic [Co(en)v2Ov2CO]^+ Cl^– and enantiopure (S)-[Hv3NCH((CH2)nNHMe2)CHv2NHv3]^3+ 3Cl^– (n = 1-4) are combined (water/ charcoal/100 °C) to give [Co(en)v2((S)-Hv2NCH((CHv2)vnNMev2H)CHv2NHv2)]4^+ 4Cl^–. The cobalt diastereomers (Δ/Δ)are separated via chiral Sephadex columns. Reactions with NaOH and Na^+ BArvf^– give the catalysts Λ- or Δ-[Co(en)v2((S)-Hv2NCH- ((CHv2)nNMev2)CHv2NHv2)]^3+ 3BArvf^–. Under optimized condition, Λ-[Co(en)v2((S)- Hv2NCH((CHv2)v3NMev2)CHv2NHv2)]^3+ 3BArvf^– gives addition products up to 98% yield and 99% ee. Section 8 describes an optimized procedure for the synthesis of highly fluorous Na^+ B(3,5-Cv6Hv3((CFv2)5CFv3)v2)v4– and its application in transporting polycations into fluorous media

Prevalence and pattern of amblyopia among children attending at tertiary eye care centre in Eastern India

Background: The objective of this study was to determine the prevalence and pattern of amblyopia of children attending at tertiary eye care centre in eastern India.Methods: A cross-sectional study was conducted from April 2020 to May2021 among children (5-15 years age) at regional institute of ophthalmology, medical college, Kolkata, underwent visual acuity assessment, detailed ocular examinations and cycloplegic refractions.Results: A total of 500 children are taken in the study, out of which 264 (52.8%) were males. The age range was 5-15 years with 479 (95.8%) within the ages of 5 to 10 years. Amblyopia was detected in 57 (11.4%). Refractive amblyopia (58.4%) was the most common type of amblyopia out of which anisometropic amblyopia accounted for 74.6%. Unilateral amblyopia was observed in 80.5%. All the types of amblyopia were more common within the age group of 5-10 years.Conclusions: More common children are affected with amblyopia within the ages of 5 to 10 years with refractive amblyopia

Packing directed beneficial role of 3-D rigid alicyclic arms on the templated molecular aggregation problem

Subtle changes in molecular structure have been used to alter the molecular packing and optical properties of organic luminophores. Thus it is important to study simple and advantageous structural modification to overcome limitations of aggregation quenching of fluorescence. Planar conjugated organic compounds are unlikely to be used in OLED devices as they suffer with luminescence weakening due to pi-pi cofacial stacking and excimer formation in the solid state. To avoid such critical issues, doped device architecture for OLED devices has widely been adopted which actually complicates the device fabrication process. Thus an approach for delimiting these drawbacks using simple methodologies is highly desirable for cost effective OLED device fabrication. In this context, two 3-dimensional rigid arms have been introduced into a planar benzo[h]chromen-2-one core, which suffers from aggregation caused quenching, as peripheral substituents to tune the molecular packing and subsequently their optical properties. The resultant compounds 1 and 2 have been tested for non-doped and doped OLED device application. Compound 1 was found to be highly thermally stable with a decomposition temperature of 344 degrees C. Single crystal XRD studies helped to elucidate that voluminous ring substituents are capable of eradicating co-facial pi-pi stacking by increasing the intermolecular distance and hence the luminescence in the solid state could be regenerated. This tuning of intermolecular distance between molecules helped to mitigate the close packed arrangement at a molecular level and also provided the bulk with the enhanced emission property. Electroluminescence from a pristine layer of compound 1 was possible. Thus an approach enabling planar luminophores to be used in OLED applications utilizing thin films of structurally engineered luminophores has been presented

Cloning and characterization of mutL and mutS genes of Vibrio cholerae: nucleotide sequence of the mutL gene

The mutL and mutS genes of Vibrio cholerae have been identified using interspecific complementation of Escherichia coli mutL and mutS mutants with plasmids containing the gene bank of V. cholerae. The recombinant plasmid pJT470, containing a 4.7 kb fragment of V. cholerae DNA codes for a protein of molecular weight 92,000. The product of this gene reduces the spontaneous mutation frequency of the E. coli mutS mutant. The plasmid, designated pJT250, containing a 2.5 kb DNA fragment of V. cholerae and coding for a protein of molecular weight 62,000, complements the mutL gene function of E. coli mutL mutants. These gene products are involved in the repair of mismatches in DNA. The complete nucleotide sequence of mutL gene of V. cholerae has been determined

IMPLEMENTATION OF NANOFLUIDS IN PLATE HEAT EXCHANGER: A REVIEW

ABSTRAC