Severity: Warning
Message: file_get_contents(https://...@pubfacts.com&api_key=b8daa3ad693db53b1410957c26c9a51b4908&a=1): Failed to open stream: HTTP request failed! HTTP/1.1 429 Too Many Requests
Filename: helpers/my_audit_helper.php
Line Number: 176
Backtrace:
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 176
Function: file_get_contents
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 250
Function: simplexml_load_file_from_url
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 1034
Function: getPubMedXML
File: /var/www/html/application/helpers/my_audit_helper.php
Line: 3152
Function: GetPubMedArticleOutput_2016
File: /var/www/html/application/controllers/Detail.php
Line: 575
Function: pubMedSearch_Global
File: /var/www/html/application/controllers/Detail.php
Line: 489
Function: pubMedGetRelatedKeyword
File: /var/www/html/index.php
Line: 316
Function: require_once
A series of new pincer-type tridentate o-aryloxide-N-heterocyclic carbene nickel complexes Ni1-Ni3 were synthesized, and the molecular structure of Ni3 was confirmed by X-ray crystallography. In comparison with the above tridentate complexes, the bidentate bis(aryloxide-NHC) nickel complex Ni4 was also synthesized. On activation with either EtAlCl or MeAlCl, all nickel complexes showed low activity toward norbornene (NB) homopolymerization. Surprisingly, Ni1-Ni3 catalysts exhibited moderate to high activity toward the homopolymerization (up to 3.21 × 10 g PNB (mol of Ni) h) and copolymerization of norbornene with 1-octene (up to 1.39 × 10 g polymer (mol of Ni) h) with B(CF) as the cocatalyst even at 100 °C, showing that tridentate nickel catalysts have high thermal stability. Notably, the tridentate Ni1-Ni3 complexes showed better activities than the corresponding bidentate bis(aryloxide-NHC) nickel complex Ni4. The obtained poly(NB-co-1-octene)s were confirmed to be vinyl-addition copolymers, which exhibited high 1-octene insertion ratio (9%-17%), good thermal stability (T > 400 °C), high molecular weight (up to 10), and narrow molecular weight distribution (PDI ≤ 1.91).
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Source |
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http://dx.doi.org/10.1039/c7dt03928j | DOI Listing |
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