Near-Infrared Light Emitting Chromium(III) Complexes - Design and Advanced Applications 2.0

基于在尼罗铬中获得的知识和申请者在配体设计、配位化学、计算化学、光化学、定量光学光谱、纳米技术和传感器材料设计方面的互补专业知识，该联合项目的开创性目标是合理设计和建立基于地球上丰富的铬(III)-分子红宝石-在新应用中的新型配合物，目前尚不适用于3D金属配合物或部分4d/5d金属配合物。这将涉及调整吸收特性、发射能量、(辐射)寿命和氧气灵敏度，以使分子红宝石的应用超越迄今报道的那些，利用理论指导的、合理设计的配体用于同向和异向铬(III)配合物。这将包括具有六元螯合环的配体用于大的配位场分裂，电子给予/接受配体以从橙色/红色到近红外的目标发射能量，用于增强配位场吸收(解决可见光中的摩尔吸收系数)和自旋反转发射(解决辐射速率)的配体，以及具有负电荷的配体以部分补偿铬(III)离子的高正电荷。此外，还将探索通过反阴离子缔合来调节磷光寿命和O2灵敏度。新的铬(III)配合物在光催化、上转换(UC)、圆偏振发光(CPL)、寿命复用和单线态氧产生等方面具有潜在的应用前景。我们将共同探索以下目标：a)同质和异色铬(III)配合物的新配体设计和新的合成方法；b)通过多参考方法(CASSCF-NEVPT2)的量子化学计算来预测铬(III)自旋-反转发射体的发射能量移动，并通过激发态密度和自旋-轨道耦合获得关于系间交叉(ISC)速率的信息。ISC速率将由飞秒瞬变吸收光谱和飞秒瞬变X射线发射光谱实验确定。C)具有合适的基态和激发态氧化还原电势的铬(III)敏化剂的激发态能量和电子转移催化作用，如敏化的[2+2]、[3+2]和[4+2]环加成反应。d)用于CPL激光器的手性铬(III)络合物的CPL性质e)使用具有合适的双激发态2E/2T1能量的铬(III)络合物作为有机染料敏化的三重态-三重态湮没上转换(STTA-UC)的供体。F)探索半导体量子点能否敏化STTA-UC体系中的铬(III)络合物。G)评估分子红宝石作为终生多路传输的标记。H)在细胞研究中使用不同电荷的铬(III)络合物作为单线态氧光敏剂，并用于诱导DNA双链断裂。

Based on the knowledge gained in NILE-CHROME and complementary expertise of the applicants in ligand design, coordination chemistry, computational chemistry, photochemistry, quantitative optical spectroscopy, nanotechnology, and design of sensor materials, the ground-breaking objectives of this joint project are to rationally design and establish novel complexes based on earth-abundant chromium(III) – the molecular rubies – in novel applications, unavailable for 3d metal complexes or partially even 4d/5d metal complexes so far. This will involve tuning absorption properties, emission energies, (radiative) lifetimes, and O2 sensitivity to enable applications of molecular rubies beyond those reported so far exploiting theory-guided, rationally designed ligands for homo- and heteroleptic chromium(III) complexes. This will include ligands with six-membered chelate rings for a large ligand field splitting, electron dona¬ting/accepting ligands to target emission energies from orange/red to the NIR, ligands to enhance ligand field absorption (tackling the molar absorption coefficient in the visible) and spin-flip emission (tackling the radiative rate) as well as ligands with a negative charge to partially compensate the chromium(III) ion’s high positive charge. Also, tuning of the phosphorescence lifetime and O2 sensitivity by counter anion association will be explored. The application potential of the novel chromium(III) complexes will be shown for photocatalysis, upconversion (UC), circularly polarized luminescence (CPL), lifetime multiplexing, and singlet oxygen generation.The following objectives will be jointly explored:a) Novel ligand designs and novel synthesis procedures for homo- and heteroleptic chromium(III) complexes.b) Excited state landscape design by quantum chemical calculations with multireference methods (CASSCF-NEVPT2) to predict emission energy shifts of chromium(III) spin-flip emitters and obtain information on intersystem crossing (ISC) rates via density of excited states and spin-orbit couplings. ISC rates will be determined experimentally by fs transient absorption spectroscopy and fs transient X-ray emission spectroscopy. c) Excited state energy and electron transfer catalysis of chromium(III) sensitizers with suitable ground and excited state redox potentials like sensitized [2+2], [3+2] and [4+2] cycloadditions.d) CPL properties of chiral chromium(III) complexes for use in a CPL laser e) Use of chromium(III) complexes with suitable doublet excited state 2E/2T1 energies as donors for sensitized triplet-triplet annihilation upconversion (sTTA-UC) with organic dyes. f) Explore whether chromium(III) complexes in sTTA-UC systems can be sensitized with semiconductor quantum dots. g) Assess molecular rubies as labels for lifetime multiplexing. h) Use differently charged chromium(III) complexes as singlet oxygen photosensitizer in cellular studies and for inducing DNA double strand breaks.