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Herein, a library of [N, N, X] tridentate iminopyridine iron chloride pre-catalysts (Fe 1\u20134) with the side arm were synthesized and confirmed by the element analysis and HRMS. All the iron compounds served as highly efficient pre-catalysts for 3,4-enhanced (up to 62%) isoprene polymerization when 500 equivalent MAOs were utilized as co-catalysts, delivering the corresponding high-performance polyisoprenes. Furthermore, optimization via single factor and response surface method, it was observed that the highest activity was obtained by complex Fe 2 with 4.0889 \u00d7 107 g\u00b7mol(Fe)\u22121\u00b7h\u22121 under the following conditions: Al\/Fe = 683; IP\/Fe = 7095; t = 0.52 min.<\/jats:p>","DOI":"10.3390\/polym15051231","type":"journal-article","created":{"date-parts":[[2023,3,1]],"date-time":"2023-03-01T01:36:09Z","timestamp":1677634569000},"page":"1231","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":14,"title":["3,4-Enhanced Polymerization of Isoprene Catalyzed by Side-Arm Tridentate Iminopyridine Iron Complex with High Activity: Optimization via Response Surface Methodology"],"prefix":"10.3390","volume":"15","author":[{"given":"Zhenyu","family":"Han","sequence":"first","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yongqiang","family":"Zhang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4054-4593","authenticated-orcid":false,"given":"Liang","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guangqian","family":"Zhu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jia","family":"Kuang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Guangyu","family":"Zhu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8557-1192","authenticated-orcid":false,"given":"Guangqiang","family":"Xu","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-1851-7078","authenticated-orcid":false,"given":"Qinggang","family":"Wang","sequence":"additional","affiliation":[{"name":"Key Laboratory of Biobased Materials, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2023,2,28]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"149","DOI":"10.1002\/pi.3223","article-title":"Bio-inspired cationic polymerization of isoprene and analogues: State-of-the-art","volume":"61","author":"Ouardad","year":"2012","journal-title":"Polym. 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