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

基于在nole - chrome项目中获得的知识，以及申请者在配体设计、配位化学、计算化学、光化学、定量光谱学、纳米技术和传感器材料设计方面的互补专业知识，该联合项目的突破性目标是合理设计和建立基于地球上丰富的铬（III）的新型配合物（分子红宝石），用于新型应用。目前3d金属配合物或部分4d/5d金属配合物不可用。这将涉及调整吸收特性、发射能量、（辐射）寿命和氧敏感性，以使分子红宝石的应用超越迄今为止所报道的那些利用理论指导、合理设计的同源和异源性铬（III）配合物配体的研究。这将包括具有六元螯合环的配体，用于大配体场分裂，电子捐赠/接受配体，以瞄准从橙色/红色到近红外的发射能量，增强配体场吸收（解决可见的摩尔吸收系数）和自旋翻转发射（解决辐射率），以及带负电荷的配体，以部分补偿铬（III）离子的高正电荷。此外，将探讨通过反阴离子缔合调节磷光寿命和氧敏感性。新型铬（III）配合物在光催化、上转换（UC）、圆极化发光（CPL）、寿命复用和单线态制氧等方面的应用潜力。以下目标将共同探讨：a)新的配体设计和新的合成方法，为同源和异交铬（III）配合物。b)利用多参考方法（CASSCF-NEVPT2）的量子化学计算设计激发态景观，预测铬（III）自旋翻转发射体的发射能量位移，并通过激发态密度和自旋轨道耦合获得系统间交叉（ISC）速率的信息。ISC速率将通过fs瞬态吸收光谱和fs瞬态x射线发射光谱进行实验测定。c)具有合适的基态和激发态氧化还原电位的铬（III）敏化剂（如敏化的[2+2]、[3+2]和[4+2]环）的激发态能量和电子转移催化作用。d) CPL激光器中使用的手性铬（III）配合物的CPL性质e)利用具有合适的双激发态2E/2T1能量的铬（III）配合物作为有机染料敏化三重态-三重态湮灭上转化（sTTA-UC）的供体。f)探索sTTA-UC体系中的铬（III）配合物是否可以用半导体量子点敏化。g)评估分子红宝石作为终身复用的标签。h)在细胞研究中使用不同电荷的铬（III）配合物作为单线态氧光敏剂，并诱导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.