Solvent Effects and Side Reactions in Organocatalyzed Atom Transfer Radical Polymerization for Enabling the Controlled Polymerization of Acrylates Catalyzed by Diaryl Dihydrophenazines.
Solvent Effects and Side Reactions in Organocatalyzed Atom Transfer Radical Polymerization for Enabling the Controlled Polymerization of Acrylates Catalyzed by Diaryl Dihydrophenazines.
复制标题
DOI：
10.1021/acs.macromol.0c02245.s001
复制
发表时间：
2020-10
期刊：
影响因子：
5.5
通讯作者：
Blaine G. McCarthy;Steven M. Sartor;J. Cole;N. Damrauer;G. Miyake
中科院分区：
文献类型：
--
作者：
Blaine G. McCarthy;Steven M. Sartor;J. Cole;N. Damrauer;G. Miyake
研究了溶剂对N，N-二(2-萘基)-5，10-二氢吩嗪(PC-1)光物理和氧化还原性能的影响，揭示了使用四氢呋喃(THF)来调节PC-1的反应性以实现可控的有机催化原子转移径向聚合(O-ATRP)的可能性。与二甲基乙酰胺(DMAc)相比，在四氢呋喃(THF)中，PC1具有更高的系间交叉量子产率(ΦISC=0.02，THF为0.30)、更长的单态激发态寿命(τ单态寿命DMAc=3.81 ns，THF为21.5 ns)和更长的三重态激发态寿命(DMAc中τ三重态=4.3μS，THF中为15.2μS)。聚合失活剂1·+在四氢呋喃中的失稳导致该物种的氧化电位增加12 0 mV(在DMAc中为0.2 2V vs SCE，在四氢呋喃中为0.34V)。PC1催化的丙烯酸正丁酯(n-BA)在四氢呋喃中比在DMAc中以更可控的方式进行，生成分散度较低的P(n-BA，Đ(Đ<1.2)。模型反应和光谱实验表明，在聚合过程中，两个引发剂衍生的烷基自由基添加到PC 1的核心形成了烷基取代的光催化剂(2)。PC2进入比PC1高约40 meV的极性CT激发态，形成氧化程度稍高的自由基阳离子(在DMAc中，1·+的E1/2 0=0.2 2V，2·+的0.2 5V)。开发了一种新的O-ATRP方法，其中PC 1原位转化为2。这种方法的应用使一些丙烯酸酯的O-ATRP值得到了中等到良好的控制(Đ=1.15-1.45，I*=83-127%)。
Investigation of the effects of a solvent on the photophysical and redox properties of the photoredox catalyst (PC), N,N-di(2-naphthyl)-5,10-dihydrophenazine (PC 1), revealed the opportunity to use tetrahydrofuran (THF) to modulate the reactivity of PC 1 toward achieving a controlled organocatalyzed atom transfer radial polymerization (O-ATRP) of acrylates. Compared with dimethylacetamide (DMAc), in tetrahydrofuran (THF), PC 1 exhibits a higher quantum yield of intersystem crossing (ΦISC = 0.02 in DMAc, 0.30 in THF), a longer singlet excited-state lifetime (τ Singlet = 3.81 ns in DMAc, 21.5 ns in THF), and a longer triplet excited-state lifetime (τ Triplet = 4.3 μs in DMAc, 15.2 μs in THF). Destabilization of 1 •+, the proposed polymerization deactivator, in THF leads to an increase in the oxidation potential of this species by 120 mV (E 1/2 0 = 0.22 V vs SCE in DMAc, 0.34 V vs SCE in THF). The O-ATRP of n-butyl acrylate (n-BA) catalyzed by PC 1 proceeds in a more controlled fashion in THF than in DMAc, producing P(n-BA) with low dispersity, Đ (Đ < 1.2). Model reactions and spectroscopic experiments revealed that two initiator-derived alkyl radicals add to the core of PC 1 to form an alkyl-substituted photocatalyst (2) during the polymerization. PC 2 accesses a polar CT excited state that is ~40 meV higher in energy than PC 1 and forms a slightly more oxidizing radical cation (E 1/2 0 = 0.22 V for 1 •+ and 0.25 V for 2 •+ in DMAc). A new O-ATRP procedure was developed wherein PC 1 is converted to 2 in situ. The application of this method enabled the O-ATRP of a number of acrylates to proceed with moderate to good control (Đ = 1.15-1.45 and I* = 83-127%).