Hydrophilic tetracarboxy bacteriochlorins for photonics applications.
Hydrophilic tetracarboxy bacteriochlorins for photonics applications.
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DOI：
10.1039/c3ob41791c
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发表时间：
2014-01
影响因子：
3.2
通讯作者：
J. Jiang;Pothiappan Vairaprakash;Kanumuri Ramesh Reddy;Tuba Sahin;M. Pavan;E. Lubian;J. Lindsey
中科院分区：
文献类型：
--
作者：
J. Jiang;Pothiappan Vairaprakash;Kanumuri Ramesh Reddy;Tuba Sahin;M. Pavan;E. Lubian;J. Lindsey
细菌素在近红外(NIR，700-900 nm)区域有很强的吸收，因此非常适合于光物理研究和光医学应用，但到目前为止，这种努力在很大程度上受到了细菌素大环固有的亲脂性的限制。在这里，研究了一种新的分子设计，其中3，5-二羧基苯基被加到细菌氯的β-吡咯基位置上。使用3，5-芳基取代基序将羧酸基团放置在细菌氯大环平面的上方和下方，这些基团在中性pH下是阴离子。采用从头合成的方法合成了五个这样的细菌素，它使用两个新的2，12-二溴细菌素积木和一个已知的3，13-二溴细菌素作为中间体。通过Suzuki偶联引入具有保护的羧酸盐部分的芳基；随后的去保护提供亲水性细菌素。后者在DMF和磷酸盐缓冲溶液(PH 7)中的吸收光谱和荧光光谱进行了表征。在大多数情况下，在磷酸盐缓冲溶液和二甲基甲酰胺中观察到类似的尖锐发射(∼的半高宽为25 nm)和适度的荧光产率(0.060-0.11)。通过对具有路径长度倒数变化的1000倍浓度范围内的样品(∼0.5、5、50和500μM；10、1、0.1和0.01 cm路径长度试管)的吸收光谱询问来检查水的溶解性。制备了一种亲水性细菌素，其中含有用于生物偶联的单一马来酰亚胺端基；该链段通过细菌素的15-溴化、Suzuki偶联和DCC介导的酰胺形成的顺序安装。将马来酰亚胺-细菌素偶联到细菌光合作用捕光复合体的一个成分的48个残基的半胱氨酸多肽类似物上。综上所述，这些结果显示了一种新的分子设计和简便的从头合成路线来获得亲水性细菌素，如果需要的话，可以得到一个生物可结合的基团。
Bacteriochlorins absorb strongly in the near-infrared (NIR, 700-900 nm) region and hence are well suited for photophysical studies and photomedical applications, yet such endeavors heretofore have been largely limited by the intrinsic lipophilicity of the bacteriochlorin macrocycle. Here, a new molecular design is investigated wherein 3,5-dicarboxyphenyl units are appended to the β-pyrrolic positions of the bacteriochlorin. Use of the 3,5-aryl substitution motif places the carboxylic acid groups, which are anionic at neutral pH, above and below the plane of the bacteriochlorin macrocycle. A de novo synthesis has been employed to create five such bacteriochlorins, which uses as intermediates two new 2,12-dibromobacteriochlorin building blocks and a known 3,13-dibromobacteriochlorin. The aryl groups with protected carboxylate moieties were introduced by Suzuki coupling; subsequent deprotection afforded the hydrophilic bacteriochlorins. The latter were characterized by absorption and fluorescence spectroscopy in DMF and in aqueous phosphate buffer (pH 7). In most cases, comparable sharp emission (FWHM of ∼25 nm) and modest fluorescence yields (0.060-0.11) were observed in aqueous phosphate buffer medium and in DMF. Aqueous solubility was examined by absorption spectral interrogation of samples over a 1000-fold concentration range with reciprocal change in pathlength (∼0.5, 5, 50, and 500 μM; 10, 1, 0.1, and 0.01 cm pathlength cuvettes). One hydrophilic bacteriochlorin was prepared that contains a single maleimido-terminated tether for bioconjugation; the tether was installed by the sequence of 15-bromination of the bacteriochlorin, Suzuki coupling, and DCC-mediated amide formation. The maleimido-bacteriochlorin was conjugated to a 48-residue cysteine-containing peptide analogue of a constituent from a bacterial photosynthetic light-harvesting complex. Taken together, the results show a new molecular design and facile de novo synthetic route for obtaining hydrophilic bacteriochlorins including a bioconjugatable group if desired.