Single-Pot Self-Assembly of Heteroleptic Mn(I)-Based Aminoquinonato-Bridged Ester/Amide-Functionalized Dinuclear Metallastirrups: Potential Anticancer and Visible-Light-Triggered CORMs

Multicomponent self-assembly of Mn2(CO)10, a bis-chelating aminoquinonato (ON∩ON)
bridge (L), and an
ester/amide-functionalized flexible neutral ditopic linker (L′)
has resulted into the formation of M2LL′-type manganese­(I)-based
dinuclear metallastirrups of general formula [{(CO)3Mn­(μ-η4-L)­Mn­(CO)3}­(μ-L′)] (1–10). Compounds 1–10 were accomplished via orthogonal bonding of the aminoquinone ligand
(2,5-bis­(n-butylamino)-1,4-benzoquinone/2,5-bis­(phenethylamino)-1,4-benzoquinone)
and ditopic pyridyl ligand to manganese carbonyl. The resultant metallastirrups
were characterized using elemental analyses and IR, UV–vis, 1H NMR, and electrospray ionization-mass spectroscopic techniques.
The molecular structure of 6 was confirmed by single-crystal
X-ray diffraction methods. Furthermore, molecular recognition capabilities
of 1, 5, 7, and 9 were evaluated with aromatic compounds containing hydroxy/amine
functionalities. Anticancer activities of compounds 1−3, 5−7, 9, and 10 were investigated against three cancer
cell lines, that is, lung (A549), colon (HCT-15), and cervical (HeLa)
as well as on normal cells (HEK 293). Compound 9 showed
a broad-spectrum inhibition toward these cancer cells upon exposure
to visible light. The myoglobin assay was performed using UV–vis
absorption spectroscopy to investigate the visible-light-triggered
CO release from 5 and 9 that could be related
to their ability to effectively inhibit cancer cells. In addition,
morphological studies confirmed the induction of autophagy due to
the treatment of cancer cells using compound 9.

以十羰基二锰(Mn₂(CO)₁₀)、双螯合氨基醌类（ON∩ON）桥联配体(L)以及酯/酰胺官能化柔性中性双齿连接配体(L')为原料，通过多组分自组装策略成功合成了通式为[{(CO)₃Mn(μ-η⁴-L)Mn(CO)₃}(μ-L')]（1~10）的M2LL'型一价锰基双核金属镫形配合物。化合物1~10可通过氨基醌配体（2,5-二(正丁基氨基)-1,4-苯醌/2,5-二(苯乙氨基)-1,4-苯醌）与双齿吡啶类配体分别与羰基锰进行正交配位得到。所得金属镫形配合物均通过元素分析、红外(IR)光谱、紫外-可见(UV–vis)光谱、氢核磁共振(¹H NMR)以及电喷雾电离质谱技术进行了表征。配合物6的分子结构通过单晶X射线衍射技术得以确证。此外，针对化合物1、5、7和9，以含羟基/胺基官能团的芳香族化合物为底物，评估了其分子识别能力。进一步考察了化合物1~3、5~7、9及10对三种癌细胞系——肺腺癌细胞(A549)、结肠癌细胞(HCT-15)、宫颈癌细胞(HeLa)以及正常胚肾细胞(HEK 293)的抗癌活性。实验发现，化合物9在可见光照射下对上述癌细胞展现出广谱抑制活性。采用紫外-可见吸收光谱开展肌红蛋白实验，以探究化合物5和9在可见光触发下的一氧化碳(CO)释放行为，该行为与其高效抑制癌细胞的能力密切相关。此外，形态学研究证实，化合物9处理癌细胞可诱导细胞自噬的发生。