Phosphorus-based 3D functional materials

• Applicant: Privatdozent Dr. Carlos Romero Nieto
• Subject Area: Organic Molecular Chemistry - Synthesis and Characterisation ; Synthesis and Properties of Functional Materials
• Term: from 2017 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 381857201

• Final Report Year: 2022

Final Report Abstract

Systems based on six-membered phosphorus heterocycles are some of the least developed molecules. The goal of this work was to prepare novel p-conjugated molecules containing two six-membered phosphorus heterocycles and investigate their properties into well-organized 3D architectures. As unexpected results in the course of this project, the synthesis of the planned phospha-molecules turned to be more than tedious than expected. In an effort to circumvent the preparative problems, we developed a series of cyclization methods that allowed to synthesize and develop the chemistry of the novel phosphahexaarenes and phosphapyrenes, both containing two six-membered phosphorus heterocycles. The investigation of their properties together with those of the model phosphaphenalenes shed light, for the first time, into the potential of this type of phosphorus heterocycles for materials science and, particularly, for the preparation of multifunctional materials. The results of this project emphasized that indeed systems based on six-membered phosphorus heterocycles are photo- and chemically stable; a fundamental question that was still uncertain. The phosphorus atoms of this type of heterocycles could be readily and reversibly functionalized with oxidizing agents, Lewis acids and transition metals. This could be utilized, for example, for the preparation of novel anticancer drugs. The phosphorus functionalizations led to unique hyperconjugative effects, which are different in five-, six- and seven-membered phosphorus heterocycles. Inserting phosphorus atoms into conjugated, aromatic structures led to ambipolar redox features and remarkable fluorescence properties. Both the functionalization of the phosphorus atoms and extension of the conjugation strongly impacted the optoelectronic properties of molecules based on six-membered phosphorus heterocycles. This is extremely attractive to develop materials whose properties could be tailored to specific applications. Although the construction of 3D assemblies through covalent interactions remains undone, building-up 3D architecture through soft interactions is indeed feasible with systems based on phosphorus heterocycles; the phosphorus atom can serve as an additional anchoring group to direct the subtle organization of molecules. Directing the assembly of molecules with attractive optoelectronic properties is an ever-ongoing hurdle to overcome. Thus, this work resulted in research concepts that will be intensively investigated by our group in the coming years.

Publications

• A Guide for the Design of Functional Polyaromatic Organophosphorus Materials. Chemistry – A European Journal, 23(56), 13919-13928.
  Hindenberg, Philip; López‐Andarias, Alicia; Rominger, Frank; de Cózar, Abel & Romero‐Nieto, Carlos
  
• Intramolecular SEAr Reactions of Phosphorus Compounds: Computational Approach to the Synthesis of π‐Extended Heterocycles. Chemistry – A European Journal, 23(69), 17487-17496.
  Larrañaga, Olatz; Romero‐Nieto, Carlos & de, Cózar Abel
  
• Diphosphahexaarenes as Highly Fluorescent and Stable Materials. Angewandte Chemie, 130(46), 15377-15381.
  Hindenberg, Philip; Busch, Marvin; Paul, Alexander; Bernhardt, Moritz; Gemessy, Patrick; Rominger, Frank & Romero‐Nieto, Carlos
  
• Highlights on π-systems based on six-membered phosphorus heterocycles. Dalton Transactions, 47(31), 10344-10359.
  Regulska, Elzbieta & Romero-Nieto, Carlos
  
• From Phosphaphenalenes to Diphosphahexaarenes: An Overview of Linearly Fused Six‐Membered Phosphorus Heterocycles. European Journal of Inorganic Chemistry, 2019(11-12), 1519-1528.
  Regulska, Elzbieta; Hindenberg, Philip & Romero‐Nieto, Carlos
  
• Intramolecular Phosphacyclization: Polyaromatic Phosphonium P‐Heterocycles with Wide‐Tuning Optical Properties. Chemistry – A European Journal, 25(25), 6332-6341.
  Belyaev, Andrey; Chen, Yi‐Ting; Liu, Zong‐Ying; Hindenberg, Philip; Wu, Cheng‐Ham; Chou, Pi‐Tai; Romero‐Nieto, Carlos & Koshevoy, Igor O.
  
• Phosphorus Post‐Functionalization of Diphosphahexaarenes. Chemistry – A European Journal, 25(57), 13146-13151.
  Hindenberg, Philip; Rominger, Frank & Romero‐Nieto, Carlos
  
• Synthesis of Blue-Luminescent Seven-Membered Phosphorus Heterocycles. The Journal of Organic Chemistry, 85(2), 1247-1252.
  Regulska, Elzbieta; Ruppert, Heiko; Rominger, Frank & Romero-Nieto, Carlos
  
• En Route Towards the Control of Luminescent, Optically‐Active 3D Architectures. Angewandte Chemie International Edition, 60(2), 766-773.
  Hindenberg, Philip; Rominger, Frank & Romero‐Nieto, Carlos
  
• Gold(i) complexes based on six-membered phosphorus heterocycles as bio-active molecules against brain cancer. Chemical Communications, 56(93), 14593-14596.
  Roesch, Saskia; Fermi, Valentina; Rominger, Frank; Herold-Mende, Christel & Romero-Nieto, Carlos
  
• Photoresponsive organophosphorus materials based on six- and seven-membered phosphorus heterocycles. Photochemistry, 376-410. Royal Society of Chemistry.
  Regulska, Elzbieta & Romero-Nieto, Carlos
  
• Controlling the molecular arrangement of racemates through weak interactions: the synergy between π-interactions and halogen bonds. Chemical Communications, 57(60), 7366-7369.
  Romero-Nieto, Carlos; de Cózar, A.; Regulska, Elzbieta; Mullenix, John B.; Rominger, Frank & Hindenberg, Philip
  
• Design of organophosphorus materials for organic electronics and bio-applications. Materials Today Chemistry, 22, 100604.
  Regulska, E. & Romero-Nieto, C.
  
• Two-Fold Intramolecular Phosphacyclization: From Fluorescent Diphosphapyrene Salts to Pentavalent Derivatives. Organic Letters, 24(35), 6391-6396.
  Hindenberg, Philip; Belyaev, Andrey; Rominger, Frank; Koshevoy, Igor O. & Romero-Nieto, Carlos