Rex Tobias, Baumert Sebastian, Hepp Alexander, Fernández Gustavo, Strassert Cristian A
Universität Münster, Institut für Anorganische und Analytische Chemie Corrensstraße 28/30 48149 Münster Germany
Universität Münster, CeNTech, CiMIC, SoN Heisenbergstraße 11 48149 Münster Germany.
Chem Sci. 2024 Oct 9;15(45):18881-7. doi: 10.1039/d4sc06096b.
Transition metal complexes are archetypal luminescent probes that are widely used for various applications ranging from optoelectronics to biomedicine. However, they face significant challenges such as photobleaching and photooxidative stress, which limit their performance. Herein, we introduce a photosystem-inspired concept based on the use of a vitamin (ascorbic acid, Asc-Ac) to adaptively suppress photobleaching of molecular luminophores. As a proof-of-concept compound, we have selected a new bis-cyclometalated Pt(II) complex (Pt-Bu) and investigated its adaptive photoluminescence resulting from singlet dioxygen (O) photoproduction in the presence of Asc-Ac. Interestingly, the excited state quenching and subsequent photobleaching of Pt-Bu in aerated solutions is suppressed by addition of Asc-Ac, which scavenges the O photosensitized by Pt-Bu upon irradiation and results in an adaptive oxygen depletion with enhancement of luminescence. The adaptation is resilient for successive irradiation cycles with oxygen replenishment, until peroxidation overshooting leads to the degradation of Pt-Bu by formation of a dark Pt(iv) species. The complexity-related adaptation with initial overperformance (luminescence boost) relies on the external energy input and cascaded feedback loops, thus biomimicking inflammation, as the repeated exposure to a stressor leads to a final breakdown. Our antioxidative protection mechanism against photobleaching can be successfully extended to multiple coordination compounds (, Ir(iii), Ru(ii) and Re(i) complexes), thus demonstrating its generality. Our findings broaden the scope of molecular adaptation and pave the way for enhancing the stability of molecular luminophores for multiple applications.
过渡金属配合物是典型的发光探针，广泛应用于从光电子学到生物医学的各种领域。然而，它们面临着诸如光漂白和光氧化应激等重大挑战，这限制了它们的性能。在此，我们引入了一种受光系统启发的概念，即利用一种维生素（抗坏血酸，Asc-Ac）来适应性地抑制分子发光体的光漂白。作为概念验证化合物，我们选择了一种新型双环金属化铂（II）配合物（Pt-Bu），并研究了其在Asc-Ac存在下由单线态氧（O）光产生导致的适应性光致发光。有趣的是，通过添加Asc-Ac可以抑制通气溶液中Pt-Bu的激发态猝灭和随后的光漂白，Asc-Ac在照射时清除由Pt-Bu光敏化的O，导致适应性氧消耗并增强发光。这种适应性对于有氧补充的连续照射循环具有弹性，直到过氧化超调导致形成深色铂（IV）物种而使Pt-Bu降解。与复杂性相关的具有初始超性能（发光增强）的适应性依赖于外部能量输入和级联反馈回路，从而模拟炎症，因为反复暴露于应激源会导致最终的崩溃。我们针对光漂白的抗氧化保护机制可以成功扩展到多种配位化合物（如铱（III）、钌（II）和铼（I）配合物），从而证明了其通用性。我们的发现拓宽了分子适应性的范围，并为提高分子发光体在多种应用中的稳定性铺平了道路。
