1
|
Ilanchezhiyan P, Mohan Kumar G, Siva C, Cho HD, Lee DJ, Lakshmana Reddy N, Ramu AG, Kang TW, Kim DY. Neodymium (Nd) based oxide perovskite nanostructures for photocatalytic and photoelectrochemical water splitting functions. Environ Res 2021; 197:111128. [PMID: 33861975 DOI: 10.1016/j.envres.2021.111128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Revised: 03/27/2021] [Accepted: 04/02/2021] [Indexed: 06/12/2023]
Abstract
Neodymium (Nd) based perovskite (Nd1-xCoxFeO3) nanostructures were processed to address the rising energy and environment crisis through offering solutions by photocatalytic and photoelectrochemical (PEC) water splitting reactions. The impact of cobalt (Co) ions on the physicochemical properties of Nd-perovskites were studied using X-ray diffraction (XRD), Raman and electron microscopic instruments. The interaction of metal ions was studied in depth via X-ray photoelectron spectroscopy (XPS). Absorption and photoluminescence signals inferred the optical band gap to be lowered and defect states to increase upon Co substitution. Improved photocatalytic efficacy in Nd1-xCoxFeO3 was evaluated by comparative studies using NdFeO3. Secondly, the enhanced conductivities in Nd1-xCoxFeO3 studied via Nyquist plot was found to be advantageous in photoelectrode fabrication for PEC functions. Time-dependent photocurrent density results affirmed the stability in processed devices. Co ions were also inferred to boost the separation of charge carriers effectively. The improved performance in Nd1-xCoxFeO3 nanostructures were well justified to the successful incorporation of Co ions that sway the Nd-O, Co-O and Co-Fe-O bondings and boost the photon absorption and electronic conductivity to facilitate the observed performance.
Collapse
Affiliation(s)
- P Ilanchezhiyan
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea; Nano-Information Technology Academy (NITA), Dongguk University, Jung-gu, Seoul, 04620, South Korea
| | - G Mohan Kumar
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea; Nano-Information Technology Academy (NITA), Dongguk University, Jung-gu, Seoul, 04620, South Korea.
| | - C Siva
- Department of Physics and Nanotechnology, SRM Institute of Science and Technology, Kattakulathur, Tamil Nadu, 603203, India
| | - H D Cho
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea
| | - D J Lee
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea
| | - N Lakshmana Reddy
- Division of Advanced Materials Engineering, Research Center of Advanced Materials Development, Jeonbuk National University, Jeonju, 54896, South Korea
| | - A G Ramu
- School of Materials Science and Engineering, Hongik University, 2639, Sejong-ro, Jochiwon-eup, Sejong, 30016, South Korea
| | - T W Kang
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea; Nano-Information Technology Academy (NITA), Dongguk University, Jung-gu, Seoul, 04620, South Korea
| | - D Y Kim
- Quantum-Functional Semiconductor Research Center (QSRC), Dongguk University, Jung-gu, Seoul, 04620, South Korea
| |
Collapse
|
2
|
Lukka Thuyavan Y, Arthanareeswaran G, Ismail A, Goh P, Shankar M, Lakshmana Reddy N. Treatment of synthetic textile dye effluent using hybrid adsorptive ultrafiltration mixed matrix membranes. Chem Eng Res Des 2020. [DOI: 10.1016/j.cherd.2020.04.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
|
3
|
Rao VN, Reddy NL, Kumari MM, Cheralathan KK, Ravi P, Sathish M, Neppolian B, Reddy KR, Shetti NP, Prathap P, Aminabhavi TM, Shankar MV. Sustainable hydrogen production for the greener environment by quantum dots-based efficient photocatalysts: A review. J Environ Manage 2019; 248:109246. [PMID: 31323456 DOI: 10.1016/j.jenvman.2019.07.017] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2019] [Revised: 07/01/2019] [Accepted: 07/06/2019] [Indexed: 05/23/2023]
Abstract
Nano-size photocatalysts exhibit multifunctional properties that opened the door for improved efficiency in energy, environment, and health care applications. Among the diversity of catalyst Quantum dots are a class of nanomaterials having a particle size between 2 and 10 nm, showing unique optoelectrical properties that are limited to some of the metal, metal oxide, metal chalcogenides, and carbon-based nanostructures. These unique characteristics arise from either pristine or binary/ternary composites where noble metal/metal oxide/metal chalcogenide/carbon quantum dots are anchored on the surface of semiconductor photocatalyst. It emphasized that properties, as well as performance of photocatalytic materials, are greatly influenced by the choice of synthesis methods and experimental conditions. Among the chemical methods, photo-deposition, precipitation, and chemical reduction, are the three most influential synthesis approaches. Further, two types of quantum dots namely metal based and carbon-based materials have been highlighted. Based on the optical, electrical and surface properties, quantum dots based photocatalysts have been divided into three categories namely (a) photocatalyst (b) co-catalyst and (c) photo-sensitizer. They showed enhanced photocatalytic performance for hydrogen production under visible/UV-visible light irradiation. Often, pristine metal chalcogenides as well as metal/metal oxide/carbon quantum dots attached to a semiconductor particle exhibit enhanced the photocatalytic activity for hydrogen production through absorption of visible light. Alternatively, noble metal quantum dots, which provide plenty of defects/active sites facilitate continuous hydrogen production. For instance, production of hydrogen in the presence of sacrificial agents using metal chalcogenides, metal oxides, and coinage metals based catalysts such as CdS/MoS2 (99,000 μmol h-1g-1) TiO2-Ni(OH)2 (47,195 μmol h-1g-1) and Cu/Ag-TiO2 nanotubes (56,167 μmol h-1g-1) have been reported. Among the carbon-based nanostructures, graphitic C3N4 and carbon quantum dots composites displayed enhanced hydrogen gas (116.1 μmol h-1) production via overall water splitting. This review accounts recent findings on various chemical approaches used for quantum dots synthesis and their improved materials properties leading to enhanced hydrogen production particularly under visible light irradiation. Finally, the avenue to improve quantum efficiency further is proposed.
Collapse
Affiliation(s)
- V Navakoteswara Rao
- Nanocatalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Kadapa, 516005, Andhra Pradesh, India
| | - N Lakshmana Reddy
- Nanocatalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Kadapa, 516005, Andhra Pradesh, India
| | - M Mamatha Kumari
- Nanocatalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Kadapa, 516005, Andhra Pradesh, India
| | - K K Cheralathan
- Department of Chemistry, School of Advanced Sciences, Vellore Institute of Technology (VIT), Thiruvalam Road, Vellore, 632014, Tamil Nadu, India
| | - P Ravi
- Functional Materials Division, Central Electrochemical Research Institute (CSIR-CECRI), Karaikudi, 630003, Tamil Nadu, India
| | - M Sathish
- Functional Materials Division, Central Electrochemical Research Institute (CSIR-CECRI), Karaikudi, 630003, Tamil Nadu, India
| | - B Neppolian
- SRM Research Institute, SRM Institute of Science and Technology, Kattankulathur, Chennai, 603203, Tamil Nadu, India
| | - Kakarla Raghava Reddy
- School of Chemical and Biomolecular Engineering, The University of Sydney, Sydney, NSW, 2006, Australia
| | - Nagaraj P Shetti
- Electrochemistry and Materials Group, Department of Chemistry, K. L. E. Institute of Technology, Affiliated to Visvesvaraya Technological University, Gokul, Hubballi, 580030, Karnataka, India
| | - P Prathap
- Photovoltaic Metrology Laboratory, National Physical Laboratory (CSIR-NPL), Dr.K.S. Krshnan Marg, New Delhi, 110012, India
| | | | - M V Shankar
- Nanocatalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Kadapa, 516005, Andhra Pradesh, India.
| |
Collapse
|
4
|
Subha N, M. M, Myilsamy M, Reddy NL, Shankar M, Neppolian B, Murugesan V. Influence of synthesis conditions on the photocatalytic activity of mesoporous Ni doped SrTiO3/TiO2 heterostructure for H2 production under solar light irradiation. Colloids Surf A Physicochem Eng Asp 2017. [DOI: 10.1016/j.colsurfa.2017.03.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
|
5
|
Reddy NL, Karthik M, Shankar MV. Synthesis of Ag–TiO2 Nanoparticles for Improved Photocatalytic Hydrogen Production Under Solar Light Irradiation. ACTA ACUST UNITED AC 2017. [DOI: 10.1166/apm.2017.1139] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
6
|
Reddy NL, Kumar S, Krishnan V, Sathish M, Shankar M. Multifunctional Cu/Ag quantum dots on TiO 2 nanotubes as highly efficient photocatalysts for enhanced solar hydrogen evolution. J Catal 2017. [DOI: 10.1016/j.jcat.2017.02.032] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
7
|
Praveen Kumar D, Lakshmana Reddy N, Srinivas B, Durga Kumari V, Shankar M. Influence of reaction parameters for the enhanced photocatalytic hydrogen production using surface modified semiconductor Titania nanotubes. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.matpr.2017.09.079] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
|
8
|
Saranya R, Arthanareeswaran G, Ismail AF, Reddy NL, Shankar M, Kweon J. Efficient rejection of organic compounds using functionalized ZSM-5 incorporated PPSU mixed matrix membrane. RSC Adv 2017. [DOI: 10.1039/c6ra27314a] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Zeolite (ZSM-5) and functionalised zeolite blended polyphenylsulfone (PPSU) mixed matrix membranes (MMMs) were fabricated for comparing their performance with virgin PPSU.
Collapse
Affiliation(s)
- R. Saranya
- Membrane Research Laboratory
- Department of Chemical Engineering
- National Institute of Technology
- Tiruchirapalli-620015
- India
| | - G. Arthanareeswaran
- Membrane Research Laboratory
- Department of Chemical Engineering
- National Institute of Technology
- Tiruchirapalli-620015
- India
| | - A. F. Ismail
- Advanced Membrane Technology Research Centre (AMTEC)
- Universiti Teknologi Malaysia
- 81310 UTM, Skudai
- Malaysia
| | - N. Lakshmana Reddy
- Nano Catalysis and Solar Fuels Research Laboratory
- Department of Materials Science & Nanotechnology
- Yogi Vemana University
- Kadapa-516003
- India
| | - M. V. Shankar
- Nano Catalysis and Solar Fuels Research Laboratory
- Department of Materials Science & Nanotechnology
- Yogi Vemana University
- Kadapa-516003
- India
| | - Jihyang Kweon
- Department of Environmental Engineering
- Konkuk University
- Seoul
- Republic of Korea
| |
Collapse
|
9
|
Praveen Kumar D, Lakshmana Reddy N, Karthikeyan M, Chinnaiah N, Bramhaiah V, Durga Kumari V, Shankar MV. Synergistic effect of nanocavities in anatase TiO2 nanobelts for photocatalytic degradation of methyl orange dye in aqueous solution. J Colloid Interface Sci 2016; 477:201-8. [PMID: 27289430 DOI: 10.1016/j.jcis.2016.05.014] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/11/2016] [Accepted: 05/11/2016] [Indexed: 10/21/2022]
Abstract
Nanocavities are empty voids exposed on the surface of one dimensional TiO2 nanostructured material. Often, they exhibited beneficial optical and electrical properties that leads to efficient photocatalytic reactions. This study reports formation of nanocavities on anatase TiO2 nanobelts (TNB) through dehydroxylation of surface hydroxyl groups during calcination process (350-600°C). The morphological and crystal structure analysis of TNB-500, -550 and -600 displayed the nanobelts shape with high density of nano-size cavities and increase in average diameter with calcination temperature. The SAED patterns confirm the anatase TiO2 phase. The enhanced light absorption properties of biphasic anatase/TiO2-B and anatase TiO2 than H2Ti3O7 are attributed to transformation of crystal structure upon calcination process. The catalytic activity was evaluated for degradation of methyl orange dye in aqueous solution under solar light irradiation. The reaction variables such as calcination temperature, amount of catalyst and pH of the methyl orange dye solution were studied and discussed in detail. Under optimal experimental conditions TNB-550 photocatalyst displayed highest degradation performance about 8 folds higher than H2Ti3O7. The high performance is explained as due to synergistic properties of one dimensional anatase TiO2 with high density of nanocavities leading to one dimensional transfer of electrons and high absorption co-efficient in UV-A spectrum are suitable for efficient red-ox reactions.
Collapse
Affiliation(s)
- D Praveen Kumar
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India
| | - N Lakshmana Reddy
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India
| | - M Karthikeyan
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India
| | - N Chinnaiah
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India
| | - V Bramhaiah
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India
| | - V Durga Kumari
- Inorganic and Physical Chemistry Division, Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, Telangana, India
| | - M V Shankar
- Nano Catalysis and Solar Fuels Research Laboratory, Department of Materials Science & Nanotechnology, Yogi Vemana University, Vemanapuram, Kadapa 516003, Andhra Pradesh, India.
| |
Collapse
|
10
|
Lakshmana Reddy N, Krishna Reddy G, Mahaboob Basha K, Krishna Mounika P, Shankar M. Highly Efficient Hydrogen Production using Bi2O3/TiO2 Nanostructured Photocatalysts Under Led Light Irradiation. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.matpr.2016.04.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
|
11
|
Kumar DP, Reddy NL, Srinivas B, Durgakumari V, Neppolian B, Shankar MV. Preparation of CuO/TiO 2 Solar Light Harvesting Nanotubular Catalysts for Proficient Hydrogen Production Using Aqueous-Glycerol Solution. ACTA ACUST UNITED AC 2015. [DOI: 10.1166/eef.2015.1162] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
|
12
|
Reddy NL, Fan W, Magar SS, Perlman ME, Yost E, Zhang L, Berlove D, Fischer JB, Burke-Howie K, Wolcott T, Durant GJ. Synthesis and pharmacological evaluation of N,N'-diarylguanidines as potent sodium channel blockers and anticonvulsant agents. J Med Chem 1998; 41:3298-302. [PMID: 9703475 DOI: 10.1021/jm980134b] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Synthesis and structure-activity relationships (SAR) are described for a series of N,N'-diarylguanidines related to N-acenaphth-5-yl-N'-(4-methoxynaphth-1-yl)guanidine (3) as anticonvulsants through blockade of sodium channels. SAR studies on compound 3 led to several simpler diphenylguanidines with improved in vitro and in vivo activity. Compounds were screened for blockade of sodium channels in a veratridine-induced [14C]guanidinium influx assay (type IIA sodium channels) and for anticonvulsant activity in the audiogenic DBA/2 mouse model. Results indicated that N, N'-diphenylguanidines substituted with flexible and moderate size lipophilic groups were preferred over aryl and/or hydrophilic groups for biological activity. Among the compounds studied, n-butyl- and/or n-butoxy-containing guanidines showed superior biological activity. A possible relationship between in vitro and in vivo activity of this compound series and their measured/calculated lipophilicities was investigated. Compounds of this series showed only weak NMDA ion channel-blocking activity indicating that the anticonvulsant activity of these compounds is unlikely to be mediated by NMDA ion channels but, more likely, by acting at voltage-gated sodium channels.
Collapse
Affiliation(s)
- N L Reddy
- Cambridge NeuroScience, Inc., Cambridge, Massachusetts 02139, USA.
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
13
|
Goldin SM, Subbarao K, Sharma R, Knapp AG, Fischer JB, Daly D, Durant GJ, Reddy NL, Hu LY, Magar S. Neuroprotective use-dependent blockers of Na+ and Ca2+ channels controlling presynaptic release of glutamate. Ann N Y Acad Sci 1995; 765:210-29. [PMID: 7486608 DOI: 10.1111/j.1749-6632.1995.tb16578.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
We have originated a family of N,N'-disubstituted guanidines that block the voltage-activated Ca2+ and Na+ channels governing glutamate release. These compounds, CNS 1237 (N-acenaphthyl-N'-methoxynaphthyl guanidine) and its analogues, are "use dependent" in their ability to attenaute neurotransmitter release: they block glutamate release with greater efficacy under conditions of persistent or repetitive depolarization, as would be encountered under pathophysiological circumstances, relative to their ability to block glutamate release elicited by brief, transient depolarizations more characteristic of normal physiological release events in nonischemic brain. Using electrophysiological and rapid kinetic methods, we have differentiated the use-dependent block of the relevant Na+ and Ca2+ channels governing neurotransmitter release from the mechanism of channel antagonism exhibited by, respectively, the substituted guanidine Na+ channel blocker tetrodotoxin (TTX) and venom peptide Ca2+ antagonists. To characterize use-dependent Na+ channel block by CNS 1237, we have employed whole-cell voltage-clamp recordings from a Chinese hamster ovary (CHO) cell line expressing cloned mammalian type II Na+ channels. These experiments demonstrated that, in contrast to the actions of TTX under the same conditions, the potency of Na+ channel block by CNS 1237 is greatly enhanced by depolarizing stimuli in a frequency-dependent manner. Ca2+ channel-activated glutamate release from brain nerve terminal preparations was measured with approximately 300 msec time resolution over a 5-second period of high K(+)-depolarization, using a rapid superfusion technique. CNS 1237 and analogues, at 1-3 microM, accelerated the decay of glutamate release by 40-70%, reflecting depolarization-induced enhancement of block. In contrast, blockade of glutamate release by the Ca2+ channel antagonist peptide toxins omega-aga IV-A (from spider venom) and omega-conotoxin M-VII-C (from cone snail venom) exhibited "reverse-use-dependence:" at concentrations of 0.3 microM, which blocked the initial amplitude of glutamate release by 40-60%, the decay time constant for glutamate release was significantly increased, indicating depolarization-induced relief of block. These findings establish that CNS 1237 and other members of this compound series are use-dependent blockers of the voltage-activated ion channels governing glutamate release. Studies of CNS 1237 in the rat middle cerebral artery occlusion (MCAO) focal stroke model have indicated infarct size reduction comparable to that observed by the same investigators for the glutamate release blocker (BW 619C89 (Burroughs-Wellcome, now in clinical development). Maximal infarct size reduction is achieved with a 3-mg/kg bolus followed by a 4-hour infusion of 0.75 mg/kg/hr.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- S M Goldin
- Cambridge NeuroScience, Massachusetts 02139, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Kirk CJ, Reddy NL, Fischer JB, Wolcott TC, Knapp AG, McBurney RN. In vitro neuroprotection by substituted guanidines with varying affinities for the N-methyl-D-aspartate receptor ionophore and for sigma sites. J Pharmacol Exp Ther 1994; 271:1080-5. [PMID: 7525936] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Radioligand binding techniques were used to determine the affinity of a series of substituted guanidine derivatives for 1) the binding site within the ion channel of the N-methyl-D-aspartate (NMDA) receptor, as defined by displacement of MK-801 ([3H]dizocilpine) and 2) sigma sites as defined by displacement of [3H]N,N'-di-(o-tolyl)guanidine. The goal was to find ligands with high affinity and selectivity for the NMDA receptor ion-channel site. The neuroprotective activity of these compounds was assessed by their ability to protect cortical neurons from injury caused by a 5-min exposure to 500 microM glutamate in vitro. Release of lactate dehydrogenase into the culture medium by damaged neurons was used as an index of neuronal injury. The 14 compounds tested had IC50 values ranging from 37.3 nM to 12.7 microM for the NMDA receptor ion-channel site and from 8.3 nM to 7.25 microM for sigma sites. Affinity for the ion-channel site was improved by unsymmetrical substitutions on the guanidine moiety. All compounds in the series protected cortical neurons against glutamate toxicity, with EC50 values (concentration affording 50% protection) ranging from 0.38 to 28.25 microM. The neuroprotective effect of each compound was positively correlated with its ion-channel site affinity (r = 0.94); no correlation between neuroprotective efficacy and sigma site binding affinity was found (r V -0.13) establishing clearly that neuroprotection in this assay was linked to NMDA antagonist properties.
Collapse
Affiliation(s)
- C J Kirk
- Cambridge NeuroScience, Inc., Massachusetts
| | | | | | | | | | | |
Collapse
|
15
|
Goldin SM, Finch EA, Reddy NL, Hu LY, Subbarao K. Exocytosis, calcium oscillations, and novel glutamate release blockers as resolved by rapid superfusion. Ann N Y Acad Sci 1994; 710:271-86. [PMID: 7908785 DOI: 10.1111/j.1749-6632.1994.tb26635.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Affiliation(s)
- S M Goldin
- Cambridge NeuroScience, Massachusetts 02139
| | | | | | | | | |
Collapse
|
16
|
Reddy NL, Hu LY, Cotter RE, Fischer JB, Wong WJ, McBurney RN, Weber E, Holmes DL, Wong ST, Prasad R. Synthesis and structure-activity studies of N,N'-diarylguanidine derivatives. N-(1-naphthyl)-N'-(3-ethylphenyl)-N'-methylguanidine: a new, selective noncompetitive NMDA receptor antagonist. J Med Chem 1994; 37:260-7. [PMID: 8295213 DOI: 10.1021/jm00028a009] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Diarylguanidines, acting as NMDA receptor ion channel site ligands, represent a new class of potential neuroprotective drugs. Several diarylguanidines structurally related to N,N'-di-o-tolylguanidine (DTG), a known selective sigma receptor ligand, were synthesized and evaluated in in vitro radioligand displacement assays, with rat or guinea pig brain membrane homogenates, using the NMDA receptor ion channel site specific radioligand [3H]-(+)-5(S)-methyl-10(R),11-dihydro-5H-dibenzo[a,d]cyclohepten-5 ,10- imine (MK-801, 3), and the sigma receptor-specific radioligand [3H]-di-o-tolylguanidine (DTG, 5). This paper presents the structure-activity relationships leading to novel tri- and tetrasubstituted guanidines, which exhibit high selectivity for NMDA receptor ion channel sites and weak or negligible affinity for sigma receptors. The in vitro binding results from symmetrically substituted diphenylguanidines indicated that compounds having ortho or meta substituents (with respect to the position of the guanidine nitrogen) on the phenyl rings showed greater affinity for the NMDA receptor ion channel site compared with para-substituted derivatives. Among the group of ring substituents studied for symmetrical diarylguanidines, an isopropyl group was preferred at the ortho position and an ethyl group was preferred at the meta position. Several unsymmetrical guanidines containing a naphthalene ring on one nitrogen atom and an ortho- or a meta-substituted phenyl ring on the second nitrogen atom, e.g., N-1-naphthyl-N'-(3-ethylphenyl)guanidine (36), showed a 3-5-fold increase in affinity for the NMDA receptor ion channel site and no change in sigma receptor affinity compared to the respective symmetrical counterparts. Additional small substituents on the guanidine nitrogen atoms bearing the aryl rings resulted in tri- and tetrasubstituted guanidine derivatives which retained affinity for NMDA receptor ion channel sites but exhibited a significant reduction in their affinities for sigma receptors. For example, N-1-naphthyl-N'-(3-ethylphenyl)-N'-methylguanidine (40) showed high affinity for the NMDA receptor ion channel site (IC50 = 36 nM vs [3H]-3) and low affinity for sigma receptors (IC50 = 2540 nM vs [3H]-5). Selectivity for the NMDA receptor ion channel sites over sigma receptors appears to be dependent upon the structure of the additional substituents on the guanidine nitrogen atoms bearing the aryl groups. Methyl and ethyl substituents are most preferred in the tri- and tetrasubstituted diarylguanidines. The trisubstituted guanidine, N-1-naphthyl-N'-(3-ethylphenyl)-N'-methylguanidine (40) and its close analogues showed good in vivo neuroprotection and are potential neuroprotective drug candidates for the treatment of stroke and other neurodegenerative disorders.
Collapse
Affiliation(s)
- N L Reddy
- Cambridge NeuroScience, Inc., Cambridge, Massachusetts 02139
| | | | | | | | | | | | | | | | | | | |
Collapse
|
17
|
Cai SX, Glenn DJ, Gee KR, Yan M, Cotter RE, Reddy NL, Weber E, Keana JF. Chlorinated phenyl azides as photolabeling reagents. Synthesis of an ortho,ortho'-dichlorinated arylazido PCP receptor ligand. Bioconjug Chem 1993; 4:545-8. [PMID: 8305523 DOI: 10.1021/bc00024a018] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The enhanced photolabeling properties of chlorinated phenyl azides are demonstrated by the synthesis and photolysis of methyl 4-azido-2,3,5,6-tetrachlorobenzoate (3) and methyl 4-azido-3,5-dichlorobenzoate (4). Photolysis of azide 3 in 1 M diethylamine/cyclohexane as the trapping medium gave 34% NH-insertion product. Similar photolysis of azide 4 gave 35% NH insertion product. These results demonstrate that chlorinated phenyl azides are significantly better at undergoing NH insertion than nonhalogenated analogs and suggest that improvement of existing aryl azide-based photolabels might be achieved by introduction of chlorine atoms on either side of the azide group. As an application, 3-azido-2,4-dichloro-10,5-(iminomethano)-10,11-dihydro-5H- dibenzo[a,d]cycloheptene (19), an analog of the potent PCP receptor ligand IDDC (14), was synthesized and its affinity for the PCP receptor was determined to be 6.3 +/- 0.7 microM (IC50 against [3H]MK801).
Collapse
Affiliation(s)
- S X Cai
- Department of Chemistry, University of Oregon, Eugene 97403
| | | | | | | | | | | | | | | |
Collapse
|
18
|
Gee KR, Barmettler P, Rhodes MR, McBurney RN, Reddy NL, Hu LY, Cotter RE, Hamilton PN, Weber E, Keana JF. 10,5-(Iminomethano)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene and derivatives. Potent PCP receptor ligands. J Med Chem 1993; 36:1938-46. [PMID: 8101572 DOI: 10.1021/jm00066a002] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
IDDC (3, 10,5-(iminomethano)-10,11-dihydro-5H-dibenzo[a,d]cycloheptene++ +) and a series of substituted derivatives were synthesized and evaluated in vitro for their ability to displace tritiated MK-801 ([3H]-2) from its specific binding site in guinea pig brain homogenate. Substitution at the 3-position of 3 with bromine, chlorine, and fluorine led to increased binding affinity. In contrast, substitution of donor groups at the 3-position gave decreased binding affinities, as did all substitutions at the 7-position and on nitrogen. Where racemic mixtures were resolved, the (+)-optical antipodes were more active than their enantiomers or racemates. The most active ligand found in this study was (+)-13e (IC50 = 15.5 +/- 4.5 nM). The affinity of (+)-13e for the PCP receptor makes it among the most potent ligands known. In vitro neuroprotection was demonstrated by 3, (+)-3, and (+)-6 (N-Me-IDDC) against glutamate-induced cell death in rat hippocampal cells.
Collapse
Affiliation(s)
- K R Gee
- Department of Chemistry, University of Oregon, Eugene 97403
| | | | | | | | | | | | | | | | | | | |
Collapse
|
19
|
McBurney RN, Daly D, Fischer JB, Hu LY, Subbarao K, Knapp AG, Kobayashi K, Margolin L, Reddy NL, Goldin SM. New CNS-specific calcium antagonists. J Neurotrauma 1992; 9 Suppl 2:S531-43. [PMID: 1319500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Ischemic insults to the brain in stroke or traumatic brain injury produce excessive release of glutamate from depolarized nerve terminals. This excessive glutamate release in turn stimulates massive calcium entry into nerve cells, activating a biochemical cascade that results in cell death. A major pathway of calcium entry into depolarized nerve cells is through voltage-sensitive, high threshold calcium channels. A large fraction of this calcium entry is mediated through "R-type" calcium channels, channels resistant to blockage by dihydropyridine calcium antagonists such as nimodipine. A newly discovered compound derived from spider venom, CNS 2103, antagonizes both R-type channels and dihydropyridine-sensitive ("L-type") calcium channels. This broad spectrum of action, coupled with selectivity for calcium channels over other classes of voltage-sensitive and ligand-gated ion channels, makes CNS 2103 an interesting lead for development of drugs to treat ischemic brain injury. Activation of presynaptic ("N-type") calcium channels in nerve terminals is a primary cause of excessive neurotransmitter release in brain ischemia. Prevention of glutamate release by blockade of N-type channels in glutamatergic nerve terminals may, at an early stage in the pathophysiological cascade, abort the process leading to nerve cell death. Cambridge NeuroScience has developed a novel rapid kinetic approach for monitoring glutamate release from brain nerve terminals in vitro, and this has led to CNS 1145, a substituted guanidine that selectively blocks a kinetic component of calcium-dependent glutamate release mediated by persistent depolarization. Additional evidence suggests that CNS 1145 antagonizes presynaptic N-type calcium channels, and this may account at least in part for its ability to block glutamate release.
Collapse
|
20
|
Scherz MW, Fialeix M, Fischer JB, Reddy NL, Server AC, Sonders MS, Tester BC, Weber E, Wong ST, Keana JF. Synthesis and structure-activity relationships of N,N'-di-o-tolylguanidine analogues, high-affinity ligands for the haloperidol-sensitive sigma receptor. J Med Chem 1990; 33:2421-9. [PMID: 1975275 DOI: 10.1021/jm00171a016] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
With an eye toward the development of novel atypical antipsychotic agents, we have studied the structure-affinity relationships of N,N'-di-o-tolylguanidine (DTG, 3) and its congeners at the haloperidol-sensitive sigma receptor. A number of DTG analogues were synthesized and evaluated in in vitro radioligand displacement experiments with guinea pig brain membrane homogenates, using the highly sigma-specific radioligands [3H]-3 and [3H]-(+)-3-(3-hydroxyphenyl)-N-(1-propyl)piperidine and the phencyclidine (PCP) receptor specific compounds [3H]-N-[1-(2-thienyl)-cyclohexyl]piperidine and [3H]-(+)-5-methyl-10,11-dihydro-5H-dibenzo[a,d]cyclohepten-5,10- imine. The affinity of N,N'-diarylguanidines for the sigma receptor decreases with increasing steric bulk of ortho substituents larger than C2H5. Hydrophobic substituents are generally preferred over similarly positioned hydrophilic ones. Furthermore, electroneutral substituents are preferred over strongly electron donating or withdrawing groups. Significant binding to the sigma receptor is usually retained as long as at least one side of the guanidine bears a preferred group (e.g. 2-CH3C6H5). Replacement of one or both aryl rings with certain saturated carbocycles (e.g. cyclohexyl, norbornyl, or adamantyl) leads to a significant increase in affinity. By combining the best aromatic and best saturated carbocyclic substituents in the same molecule, we arrived at some of the most potent sigma ligands described to date (e.g. N-exo-2-norbornyl-N'-(2-iodophenyl)guanidine, IC50 = 3 nM vs [3H]-3). All of the compounds tested were several orders of magnitude more potent at the sigma receptor than at the PCP receptor, with a few notable exceptions. This series of disubstituted guanidines may be of value in the development of potential antipsychotics and in the further pharmacological and biochemical characterization of the sigma receptor.
Collapse
Affiliation(s)
- M W Scherz
- Department of Chemistry, University of Oregon, Eugene 97403
| | | | | | | | | | | | | | | | | | | |
Collapse
|