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Kundu P, Ghosh S, Chattopadhyay N. Exploration of photophysics of 2,2′-pyridil at room temperature and 77 K: a combined spectroscopic and quantum chemical approach. Photochem Photobiol Sci 2017; 16:159-169. [DOI: 10.1039/c6pp00378h] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
TRANES and other photophysical studies of 2,2′-pyridil at RT and 77 K, supported by quantum chemical calculations, assign the dual emissions to coexistence of the two rotational conformers.
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Affiliation(s)
- Pronab Kundu
- Department of Chemistry
- Jadavpur University
- Kolkata-700032
- India
| | - Saptarshi Ghosh
- Department of Chemistry
- Jadavpur University
- Kolkata-700032
- India
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Chang YY, Ho TL, Chung WS. Deformative transition of the Menschutkin reaction and helical atropisomers in a congested polyheterocyclic system. J Org Chem 2014; 79:9970-8. [PMID: 25279831 DOI: 10.1021/jo501815y] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A 4,7-phenanthroline polycyclic 1A designed for probing the limits of the Menschutkin reaction was synthesized in a six-step sequence. The rotational barrier of the phenyl ring nearby the N-methyl group in rac-2A was estimated to be ≫ 18.1 kcal/mol from VT-NMR experiments, making them a new type of helical atropisomer. The methylation rate constants of 9 and 1A with MeI was found to be 2.22 × 10(-4) and 9.62 × 10(-6) s(-1) mol(-1) L, respectively; thus, the formation rate of (P/M)-2A is one of the slowest rates ever reported for a Menschutkin reaction. The N-methyl protons in (P/M)-2A exhibit a significant upfield shift (Δδ 1.0 ppm) in its (1)H NMR, compared to those without a nearby phenyl, indicating a strong CH-π interaction is involved. Conformational flexibility in dipyridylethene 9 is clearly shown by its complexation with BH3 to form helical atropisomers (P,P/M,M)-10. The pKa values of the conjugate acids of 1A and 9 in acetonitrile were determined to be 4.65 and 5.07, respectively, which are much smaller compared to that of pyridine 14a (pKa = 12.33), implying that the basicity, nucleophilicity, and amine alkylation rates of 1A and 9 are markedly decreased by the severe steric hindrance of the flanking phenyl rings in the polyheterocycles.
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Affiliation(s)
- Yung-Yu Chang
- Department of Applied Chemistry, National Chiao-Tung University , Hsinchu 30050, Taiwan-ROC
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Chen J, Duan W, Bai R, Yao H, Shang J, Xu J. Design, synthesis and antioxidant activity evaluation of novel β-elemene derivatives. Bioorg Med Chem Lett 2014; 24:3407-11. [PMID: 24928401 DOI: 10.1016/j.bmcl.2014.05.078] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2014] [Revised: 05/12/2014] [Accepted: 05/22/2014] [Indexed: 01/07/2023]
Abstract
Forty β-elemene derivatives were prepared and their antioxidant activity in H2O2-treated human umbilical vein endothelial cells (HUVECs) was first investigated. Among which, the dimer compounds 5r and 5s exhibited the most potent antioxidant activity against reactive oxygen species production. Meanwhile, 5r and 5s led to a significant increase in superoxide dismutase and nitric oxide levels and decrease in malonyldialdehyde and lactate dehydrogenase contents. Furthermore, MTT assay showed that 5r and 5s did not produce obvious cytotoxicity and had significantly cytoprotective effects against oxidative damage on HUVECs.
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Affiliation(s)
- Jichao Chen
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China
| | - Wenli Duan
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Center for Drug Screening, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China
| | - Renren Bai
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China
| | - Hequan Yao
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China
| | - Jing Shang
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Center for Drug Screening, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China.
| | - Jinyi Xu
- State Key Laboratory of Natural Medicines, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China; Department of Medicinal Chemistry, China Pharmaceutical University, 24 Tong Jia Xiang, Nanjing 210009, PR China.
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Yasuda D, Takahashi K, Kakinoki T, Tanaka Y, Ohe T, Nakamura S, Mashino T. Synthesis, radical scavenging activity and structure–activity relationship of uric acid analogs. MEDCHEMCOMM 2013. [DOI: 10.1039/c2md20287e] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Cheng LX, Jin XL, Teng QF, Chang J, Yao XJ, Dai F, Qian YP, Tang JJ, Li XZ, Zhou B. Antioxidant activity of α-pyridoin and its derivatives: possible mechanism. Org Biomol Chem 2010; 8:1058-63. [DOI: 10.1039/b922673g] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
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