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1.
Biochem Genet ; 61(5): 1850-1866, 2023 Oct.
Article in English | MEDLINE | ID: mdl-36869999

ABSTRACT

Autosomal short tandem repeat (STR) population data collected from a well characterized population are needed to correctly assigning the weight of DNA profiles in the courtroom and widely used for ancestral analyses. In this study, allele frequencies for the 15 autosomal short tandem repeat (STR) loci included in the AmpFlSTR® Identifiler® plus kit (D8S1179, D21S11, D7S820, CSF1PO, D3S1358, TH01, D13S317, D16S539, D2S1338, D19S433, VWA, TPOX, D18S51, D5S818, FGA) were obtained by genotyping 332 unrelated individuals of Ghanaian origin. Statistical tests on STR genotype data showed no significant departure from Hardy-Weinberg equilibrium (HWE). The overall match probability, combined power of exclusion and combined power of discrimination for these loci were 1 in 3.85 × 1017, 0.99999893 and 0.99999998, respectively. Polymorphic information content (PIC) greater than 0.70 was observed for all loci except TH01 and D13S317. These statistical parameters confirm that this combination of loci is valuable for forensic identification and parentage analysis. Our results were also compared with those for 20 other human populations analyzed for the same set of markers. We observed that the Ghanaian population grouped with other African populations in two-dimensional principal coordinate (PCO) and a neighbor-joining (N-J) data mapping and placed closest to Nigerians. This observation reflects cultural similarities and geographical factors, coupled with the long history of migration and trading activities between Ghana and Nigeria. Our report provides what we believe to be the first published autosomal STR data for the general Ghanaian population using 15 loci genotyped using the AmpFlSTR® Identifiler® plus kit methodology. Our data show that the loci tested have sufficient power to be used reliably for DNA profiling in forensic casework and help to elucidate the genetic history of people living in the country.


Subject(s)
Genetics, Population , Microsatellite Repeats , Humans , Ghana , Polymerase Chain Reaction , Gene Frequency , DNA Fingerprinting
2.
Genet Test Mol Biomarkers ; 26(9): 449-456, 2022 Sep.
Article in English | MEDLINE | ID: mdl-36166739

ABSTRACT

Introduction: Cytokines are cell signaling glycoproteins that are particularly important in immunity and inflammatory responses. Therefore, variations, such as single nucleotide polymorphisms (SNPs), in genes encoding for cytokines may have important consequences for their roles in health. Materials and Methods: A total of 222 unrelated, healthy, and un-admixed Malays (n = 97), Chinese (n = 77), and Indians (n = 48) with a median age of 30 years old (range 21-50) were typed for 22 cytokine gene SNPs: IL-1α -889 T/C, IL-1ß (-511 T/C, +3962 T/C), IL-1R pst1 1970 T/C, IL-1RA mspa1 11100 T/C, IL-4Rα +1902 G/A, IL-12 - 1188 C/A, IFN-γ +874 A/T, TGF-ß (cdn 10 C/T, cdn 25 G/C), TNF-α (-308 A/G, -238 A/G) IL-2 (+166 G/T, -330 T/G), IL-4 (-1098 T/G, -590 T/C, -33 T/C), IL-6 (-174 C/G, nt565 G/A), and IL-10 (-1082 G/A, -819 C/T, -592 A/C). This involved using well-established polymerase chain reaction procedures with sequence-specific primers and restriction fragment length polymorphism methods. Results: The majority of the screened cytokine gene SNPs are polymorphic in all three ethnicities. Exceptions include TGF-ß cdn 25 (G/C), IL-1ß +3962 (T/C), and TNF-α -238 (A/G), which were all observed to be monomorphic in Malays, Chinese and Indians. Many of the analyzed cytokine gene SNP genotypes deviated from Hardy-Weinberg equilibrium and the three ethnic study groups were all well-separated from reference Asian, African and European populations in a principal component analysis plot. Conclusion: We successfully typed 22 SNPs in 13 cytokine genes from genetic material collected from unrelated and un-admixed Malay, Chinese and Indian individuals in Peninsular Malaysia. These new cytokine gene population datasets reveal interesting contrasts with other populations.


Subject(s)
Interleukin-10 , Polymorphism, Single Nucleotide , Adult , China , Cytokines/genetics , Gene Frequency/genetics , Genotype , Humans , Interleukin 1 Receptor Antagonist Protein/genetics , Interleukin-10/genetics , Interleukin-12/genetics , Interleukin-2/genetics , Interleukin-4/genetics , Interleukin-6/genetics , Malaysia , Middle Aged , Polymorphism, Single Nucleotide/genetics , Transforming Growth Factor beta/genetics , Tumor Necrosis Factor-alpha/genetics , Young Adult
3.
Front Genet ; 13: 970549, 2022.
Article in English | MEDLINE | ID: mdl-36147511

ABSTRACT

A new era presently dawns for medical genetics featuring individualised whole genome sequencing and promising personalised medical genetics. Accordingly, we direct readers attention to the continuing value of allele frequency data from Genome-Wide Association Surveys (GWAS) and single gene surveys in well-defined ethnic populations as a guide for best practice in diagnosis, therapy, and prescription. Supporting evidence is drawn from our experiences working with Austronesian volunteer subjects across the Western Pacific. In general, these studies show that their gene pool has been shaped by natural selection and become highly diverged from those of Europeans and Asians. These uniquely evolved patterns of genetic variation underlie contrasting schedules of disease incidence and drug response. Thus, recognition of historical bonds of kinship among Austronesian population groups across the Asia Pacific has distinct public health advantages from a One Health perspective. Other than diseases that are common among them like gout and diabetes, Austronesian populations face a wide range of climate-dependent infectious diseases including vector-borne pathogens as they are now scattered across the Pacific and Indian Oceans. However, we caution that the value of genetic survey data in Austronesians (and other groups too) is critically dependent on the accuracy of attached descriptive information in associated metadata, including ethnicity and admixture.

4.
J Med Entomol ; 59(5): 1525-1533, 2022 09 14.
Article in English | MEDLINE | ID: mdl-35733165

ABSTRACT

The mosquito Aedes aegypti is the primary vector of the dengue, yellow fever, and chikungunya viruses. Evidence shows that Ae. aegypti males are polyandrous whereas Ae. aegypti females are monandrous in mating. However, the degree to which Ae. aegypti males and females can mate with different partners has not been rigorously tested. Therefore, this study examined the rates of polyandry via parentage assignment in three sets of competitive mating experiments using wild-type male and female Ae. aegypti. Parentage assignment was monitored using nine microsatellite DNA markers. All Ae. aegypti offspring were successfully assigned to parents with 80% or 95% confidence using CERVUS software. The results showed that both male and female Ae. aegypti mated with up to 3-4 different partners. Adults contributed differentially to the emergent offspring, with reproductive outputs ranging from 1 to 25 viable progeny. This study demonstrates a new perspective on the capabilities of male and female Ae. aegypti in mating. These findings are significant because successful deployment of reproductive control methods using genetic modification or sterile Ae. aegypti must consider the following criteria regarding their mating fitness: 1) choosing Ae. aegypti males that can mate with many different females; 2) testing how transformed Ae. aegypti male perform with polyandrous females; and 3) prioritizing the selection of polyandrous males and/or females Ae. aegypti that have the most offspring.


Subject(s)
Aedes , Aedes/genetics , Animals , Female , Male , Microsatellite Repeats , Mosquito Vectors/genetics , Reproduction , Sexual Behavior, Animal
5.
Animals (Basel) ; 12(7)2022 Mar 23.
Article in English | MEDLINE | ID: mdl-35405801

ABSTRACT

Numerous studies show the importance of social understanding in addressing multifaceted conservation issues. Building on a conservation planning framework, this study examines the social dimensions of wildlife conservation in Kinabatangan, Sabah, Malaysia. It employs a qualitative approach by conducting in-depth, semi-structured interviews with sixty informants drawn from local community members, government officials, tourism operators, non-government organizations, and the private sector. Our results show that the incidence of human-wildlife conflicts has reduced in the region, but that conflicts among stakeholders themselves about wildlife still remain a significant threat for attaining successful conservation outcomes. Further stakeholder perceptions of increased wildlife numbers often contrast with actual counts returned by periodical surveys conducted by conservation agencies, e.g., showing a 30% decline of orangutans and a 29% decline of gibbon abundance. This shows that evidence-based conservation messages have not been communicated well. The study has implications for enhancing social values among conservation players, promoting local community empowerment and revising conservation awareness programs.

7.
Hum Biol ; 92(4): 247-263, 2021 10.
Article in English | MEDLINE | ID: mdl-34665569

ABSTRACT

The Austronesian Diaspora is a 5,000-year account of how a small group of Taiwanese farmers expanded to occupy territories reaching halfway around the world. Reconstructing their detailed history has spawned many academic contests across many disciplines. An outline orthodox version has eventually emerged but still leaves many unanswered questions. The remarkable power of whole-genome technology has now been applied to people across the entire region. This review gives an account of this era of genetic investigation and discusses its many achievements, including revelation in detail of many unexpected patterns of population movement and the significance of this information for medical genetics.


Subject(s)
Genetics, Population , Human Migration , Asian People , Genomics , Humans , Polymorphism, Single Nucleotide
8.
Int J Legal Med ; 135(4): 1433-1435, 2021 Jul.
Article in English | MEDLINE | ID: mdl-33782746

ABSTRACT

DNA profiling of X-chromosomal short tandem repeats (X-STR) has exceptional value in criminal investigations, especially for complex kinship and incest cases. In this study, Investigator® Argus X-12 Quality Sensor (QS) kits were successfully used to characterize 12 X-STR loci in 199 unrelated healthy Kedayan individuals living in Sabah and Sarawak, Malaysia. The LG1 haplogroup (DXS8378 - DXS10135 - DXS10148) has the largest HD (0.9799) as compared with all other closely linked haplotype groups examined (LG2; DXS7132-DXS10074-DXS10079, LG3; DXS10103-DXS10101-HPRTB and LG4; DXS10134-DXS7423-DXS10146). Data from statistical analysis showed that high combined of PDM, PDF, MEC_Krüger, MEC_Kishida, MEC_Desmarais, and MEC_Desmarais_duo values (0.999999994405922, 0.99999999999999, 0.999990463834938, 0.999999975914808, 0.999999975985006, and 0.999996491927194, respectively) in the Kedayan. In a two-dimensional scaling (MDS) plot and dendrogram constructed using allele frequencies at the 12 X-STR loci, Kedayan appear to be most closely related to their other Austronesian populations including the Malays and Filipinos as compared with other reference population groups. Findings from the present study thus demonstrate high genetic variability across the 12 tested X-STR loci and can be used for population studies and forensic applications.


Subject(s)
Chromosomes, Human, X , DNA Fingerprinting/instrumentation , Ethnicity/genetics , Microsatellite Repeats , Borneo/ethnology , Female , Gene Frequency , Genetic Loci , Genetics, Population , Haplotypes , Humans , Malaysia/ethnology , Male
9.
Oman Med J ; 35(6): e189, 2020 Nov.
Article in English | MEDLINE | ID: mdl-33110633

ABSTRACT

OBJECTIVES: Blood bank centers routinely screen for hepatitis B virus (HBV), hepatitis C virus (HCV), and human immunodeficiency virus (HIV) to ensure the safety of blood supply and thus prevent the dissemination of these viruses via blood transfusion. We sought to evaluate the detection of transfusion-transmitted infection (TTI) markers using standard serological methods and nucleic acid testing (NAT) among blood donors in Hospital Universiti Sains Malaysia. METHODS: Donated blood units were assessed for the presence or absence of HBV, HCV, and HIV using two screening method: serology and NAT. Reactive blood samples were then subjected to serological confirmatory and NAT discriminatory assays. RESULTS: A total of 9669 donors were recruited from September 2017 to June 2018. Among these, 36 donors were reactive either for HBV, HCV, or HIV by serological testing and eight by NAT screening. However, only 10 (three for HBV and seven for HCV) donors tested positive using serological testing and five (two for HBV and three for HCV) by NAT discriminatory assays. Note that all five NAT positive donors detected in the NAT discriminatory assays were confirmed to be serologically reactive. Therefore, the prevalence of HBV, HCV, and HIV was 0.03%, 0.1%, and 0.0%, respectively, in our donor pool. CONCLUSIONS: Both serological and NAT screening and confirmatory assays should be used routinely to reduce the risk of infection transmission via the transfusion of blood and blood components.

10.
Genes (Basel) ; 11(10)2020 09 23.
Article in English | MEDLINE | ID: mdl-32977385

ABSTRACT

Science and technology are extensively used in criminal investigation. From the mid- to late-1980s, one of the scientific discoveries that has had a particularly remarkable impact on this field has been the use of highly variable DNA sequence regions (minisatellites) in the human genome for individual identification. The technique was initially referred to as DNA fingerprinting, but is now more widely referred to as DNA profiling. Since then, many new developments have occurred within this area of science. These include the introduction of new genetic markers (microsatellites also known as short tandem repeats/STRs), the use of the polymerase chain reaction for target amplification, the development of DNA databases (databanking), and the advancement and/or improvement of genotyping protocols and technologies. In 2019, we described the progress of DNA profiling and DNA databanking in Malaysia for the first time. This report included information on DNA analysis regulations and legislation, STR genotyping protocols, database management, and accreditation status. Here, we provide an update on the performance of our DNA databank (numbers of DNA profiles and hits) plus the technical issues associated with correctly assigning the weight of evidence for DNA profiles in an ethnically diverse population, and the potential application of rapid DNA testing in the country. A total of 116,534 DNA profiles were obtained and stored in the Forensic DNA Databank of Malaysia (FDDM) by 2019, having increased from 70,570 in 2017. The number of hits increased by more than three-fold in just two years, where 17 and 69 hits between the DNA profiles stored in the FDDM and those from crime scenes, suspects, detainees, drug users, convicts, missing persons, or volunteers were recorded in 2017 and 2019, respectively. Forensic DNA analysis and databanking are thus progressing well in Malaysia and have already contributed to many criminal investigations. However, several other issues are discussed here, including the need for STR population data for uncharacterized population groups, and pilot trials for adopting rapid DNA profiling technology. These aspects should be considered by policy makers and law enforcement agencies in order to increase the reliability and efficiency of DNA profiling in criminal cases and in kinship analysis in Malaysia.


Subject(s)
DNA Fingerprinting/methods , DNA/genetics , Databases, Nucleic Acid/statistics & numerical data , Forensic Genetics/methods , Genetic Markers , Microsatellite Repeats , DNA/analysis , Databases, Nucleic Acid/standards , Genetics, Population , Genotyping Techniques , Humans , Malaysia
11.
Data Brief ; 31: 105909, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32642519

ABSTRACT

This data article provides population frequencies for 21 autosomal and two sex determining short tandem repeat (STR) loci in unrelated Kedayan individuals. This article is related to the research paper entitled "Forensic parameters and ancestral fraction in the Kedayan population inferred using 21 autosomal STR loci" [1] where these same data were subjected to ancestry and forensic analyses. We have collected 200 blood samples consisting of 128 male and 72 female volunteer representatives from Kedayan people residing in various parts of Borneo. All 23 STR loci were simultaneously amplified using Globalfiler™ Express PCR and amplicons were separated using an ABI 3500xl Genetic Analyzer. The STR allele calls at each locus were called using GeneMapperⓇ ID-X Software v1.4, while several algorithms in Arlequin software version 3.5 were used to estimate Hardy-Weinberg equilibrium (HWE) and linkage disequilibrium (LD) between pairs of STR loci.

13.
Data Brief ; 31: 105746, 2020 Aug.
Article in English | MEDLINE | ID: mdl-32490095

ABSTRACT

Short tandem repeat (STR) loci are widely used as genetic marker for ancestral and forensic analyses. The latter application includes for paternity testing and DNA profiling of samples collected from scenes of crime and suspects. This survey provides the first dataset for 21 STR loci across the Akan population in Ghana by genotyping of 109 unrelated healthy individuals using Investigator 24plex kit. None of the STR loci screened deviated from Hardy-Weinberg equilibrium after applying Bonferroni correction. Overall, 224 unique alleles were observed with allele frequencies ranging from 0.005 to 0.518. The combined match probability, combined power of exclusion and combined power discrimination were 1 in 4.07 × 10-25, 0.999999999 and 1, respectively. Principal coordinate analysis carried out using 21 STR allele frequency data mapped the Akans with Nigerian subpopulation groups (Hausa, Igbo and Yoruba), but separated from Thais of Thailand, Chechen of Jordan and Tijuana of Mexico.

14.
Int J Legal Med ; 134(4): 1335-1337, 2020 Jul.
Article in English | MEDLINE | ID: mdl-31897667

ABSTRACT

Genetic polymorphisms at 23 Y chromosome short tandem repeat (STRs) loci included in the Powerplex® Y23 PCR kit were successfully scored in 128 unrelated Kedayan individuals living in Sabah, East Malaysia. Complete haplotypes were recorded for all individuals and included 92 different types with 72 being unique to single male subjects. Three important forensic statistics were calculated from these data; haplotype diversity = 0.993, discriminating capacity = 0.719, and match probability = 0.015. The Kedayan appear to be most closely related to Malays and Filipinos in a multidimensional scaling plot and are separated from other mainland Asia populations including Thais and Hakka Han. These new data for Kedayan have been deposited in the YHRD database (accession number: YA004621). Our statistical analyses showed the reliability of Y-STR loci for geographically extended use in forensic casework and for studying human population history.


Subject(s)
Chromosomes, Human, Y , Ethnicity/genetics , Gene Frequency , Haplotypes , Microsatellite Repeats , Polymorphism, Genetic , Humans , Malaysia/ethnology , Male , Multidimensional Scaling Analysis , Sequence Analysis, DNA
15.
Int J Legal Med ; 134(4): 1313-1315, 2020 Jul.
Article in English | MEDLINE | ID: mdl-31154498

ABSTRACT

In this study, 268 samples for unrelated males belonging to the five major human subpopulation groups in Ghana (Akan, Ewe, Mole-Dagbon, Ga-Dangme and Guang) were genetically characterised for 23 Y chromosome short tandem repeat (STR) loci using the Powerplex® Y23 STR kit. A total of 263 complete haplotypes were recorded of which 258 were unique. The haplotype diversity, discriminating capacity and match probability for the pooled population data were 0.9998, 0.9627 and 0.0039, respectively. The pairwise genetic distance (RST) for the Ghanaian datasets and other reference populations deposited in the Y-STR Haplotype Reference Database (YHRD) were estimated and mapped using multidimensional scaling (MDS) plot. The Guang and Ewe were significantly different from the Akan, Mole-Dagbon and Ga-Dangme. However, the five Ghanaian datasets were all plotted close together with other African populations in the MDS data mapping.


Subject(s)
Chromosomes, Human, Y , Ethnicity/genetics , Gene Frequency , Haplotypes , Microsatellite Repeats , Datasets as Topic , Genetics, Population , Ghana/ethnology , Humans , Male , Multidimensional Scaling Analysis
16.
Transfus Apher Sci ; 59(2): 102651, 2020 Apr.
Article in English | MEDLINE | ID: mdl-31606336

ABSTRACT

BACKGROUND: Human neutrophil antigens (HNAs) are implicated in several clinical disorders and their allelic variations have been reported for many populations. This new study was aimed to report the genotype and alleles frequencies of HNA-1, -3, -4 and -5 loci in Malays, Chinese and Indians in Peninsular Malaysia. METHODS: A total of 222 blood samples were collected from healthy, unrelated Malay, Chinese and Indian individuals. Their HNA-1, -3 and -4 and HNA-5 loci were genotyped using polymerase chain reaction-sequence specific primer (PCR-SSP) or PCR-restriction fragment length polymorphism (RFLP) assays. RESULTS: All HNA loci are polymorphic, except for HNA -4. Geneotypes HNA-1a/1b, -3a/3b and -4a/4a were observed most frequently at these three loci in all three ethnic groups. In contrast, HNA-5a/5b and -5a/5a were observed as the predominant genotypes in Malays vs. Chinese and Indians, respectively. The Malays, Chinese and Indians shared HNA -3a (0.505-0.527), HNA -4a (1.000) and -5a (0.676-0.854) as the most frequent alleles. However, HNA-1a was found to be the most common in Malays (0.506) and Chinese (0.504) and HNA-1b for Indians (0.525). CONCLUSION: Combined with HNA data that have been published for Malay subethnic and Orang Asli groups, this study provides the first fully comprehensive HNA dataset for populations to be found in Peninsular Malaysia. Overall, our findings provide further evidence of genetic complexity in the region. This now publicly available HNA dataset can be used as a reliable reference source for improving medical outcomes.


Subject(s)
Antigens/immunology , Gene Frequency/immunology , Neutrophils/immunology , Asian People , Female , Healthy Volunteers , Humans , India , Malaysia , Male
17.
Data Brief ; 26: 104449, 2019 Oct.
Article in English | MEDLINE | ID: mdl-31667222

ABSTRACT

This article provides violent crime data in Malaysia from 2006 to 2017. The violent crimes include murder, rape, gang robbery, robbery and voluntarily causing hurt cases. A total of 330,395 violent crime cases were reported in this 12 year period and the data were tabulated state by state for all thirteen states of Malaysia, including two states in Borneo (Sabah and Sarawak) and one federal territory (Kuala Lumpur). In general, violent crimes show a decreasing trend from 2006 to 2017 in Malaysia. However, armed gang robbery and armed robbery show a fluctuating pattern from 2008 to 2011. A similar pattern was also recorded for unarmed gang robbery from 2008 to 2010. The violent crime data deposited here are available for further analysis, e.g., for identifying risk factors such as demography, lifestyle, socio-economic status, government policies etc. which may be associated with violent crime incidence and pattern across the country.

18.
Chem Commun (Camb) ; 55(93): 14058-14061, 2019 Nov 19.
Article in English | MEDLINE | ID: mdl-31691686

ABSTRACT

All hydrogen atoms of the NH3 in [Mn(depe)2(CO)(NH3)]+ are abstracted by 2,4,6-tri-tert-butylphenoxyl radical, resulting in the isolation of a rare cyclophosphazenium cation, [(Et2P(CH2)2PEt2)N]+, in 76% yield. An analogous reaction is observed for [Mn(dppe)2(CO)(NH3)]+. Computations suggest insertion of NHx into a Mn-P bond provides the thermodynamic driving force. Contextualization of this reaction provides insights on catalyst design and breaking strong N-H bonds.

19.
Sci Rep ; 9(1): 14558, 2019 10 10.
Article in English | MEDLINE | ID: mdl-31601905

ABSTRACT

Short repetitive regions in autosomal and Y chromosomes known as short tandem repeats (STRs) are currently used for DNA profiling in crime investigations. However, DNA profiling requires a sufficient quality and quantity of DNA template, which is often not obtained from trace evidence or degraded biological samples collected at the scene of a crime. Here, we assessed autosomal and male DNA components extracted from crime scene and mock casework samples using the Casework Direct Kit, Custom and compared the results against those obtained by extraction of matching samples using well-established Maxwell 16 System DNA IQ Casework Pro Kit. The quantity and quality of extracted DNA obtained using both Casework Direct Kit, Custom and Maxwell 16 System DNA IQ Casework Pro Kit were analyzed using PowerQuant Systems followed by autosomal and Y-chromosome STR profiling using GlobalFiler Express PCR Amplification Kit and PowerPlex Y23 System, respectively. Our results showed that the Casework Direct Kit and Maxwell 16 DNA IQ Casework Pro Kit have more or less equal capacity to extract inhibitor free DNA, but that the latter produces slightly better quality and more DNA template and subsequently higher numbers of STR allele calls for autosomal and Y-STR analyses. Nonetheless, the Casework Direct Kit, Custom is the quicker and cheaper option for extraction of good, clean DNA from high content material and might best be used for extraction of reference samples. Such reference DNA samples typically come from buccal swabs or freshly drawn blood. So, in general, they can confidently be expected to have a high nucleic acid content and to be inhibitor-free.


Subject(s)
Chromosomes, Human, Y , DNA Fingerprinting , DNA/analysis , Forensic Genetics/instrumentation , Microsatellite Repeats , Alleles , Chromosomes , Crime , Female , Humans , Male , Polymerase Chain Reaction , Reference Values
20.
Angew Chem Int Ed Engl ; 58(34): 11618-11624, 2019 Aug 19.
Article in English | MEDLINE | ID: mdl-31115120

ABSTRACT

Catalysts for the oxidation of NH3 are critical for the utilization of NH3 as a large-scale energy carrier. Molecular catalysts capable of oxidizing NH3 to N2 are rare. This report describes the use of [Cp*Ru(PtBu 2 NPh 2 )(15 NH3 )][BArF 4 ], (PtBu 2 NPh 2 =1,5-di(phenylaza)-3,7-di(tert-butylphospha)cyclooctane; ArF =3,5-(CF3 )2 C6 H3 ), to catalytically oxidize NH3 to dinitrogen under ambient conditions. The cleavage of six N-H bonds and the formation of an N≡N bond was achieved by coupling H+ and e- transfers as net hydrogen atom abstraction (HAA) steps using the 2,4,6-tri-tert-butylphenoxyl radical (t Bu3 ArO. ) as the H atom acceptor. Employing an excess of t Bu3 ArO. under 1 atm of NH3 gas at 23 °C resulted in up to ten turnovers. Nitrogen isotopic (15 N) labeling studies provide initial mechanistic information suggesting a monometallic pathway during the N⋅⋅⋅N bond-forming step in the catalytic cycle.

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