A Comprehensive Study on Tetraaryltetrabenzoporphyrins

Abstract Tetraaryltetrabenzoporphyrins (TATBPs) show, due to their optoelectronic properties, rising potential as dyes in various fields of physical and biomedical sciences. However, unlike in the case of porphyrins, the potential structural diversity of TATBPs has been explored only to little extent, owed mainly to synthetic hurdles. Herein, we prepared a comprehensive library of 30 TATBPs and investigated their fundamental properties. We elucidated structural properties by X‐ray crystallography and found explanations for physical properties such as solubility. Fundamental electronic aspects were studied by optical spectroscopy as well as by electrochemistry and brought in context to the stability of the molecules. Finally, we were able to develop a universal synthetic protocol, utilizing a readily established isoindole synthon, which gives TATBPs in high yields, regardless of the nature of the used arylaldehyde and without meticulous chromatographic purifications steps. This work serves as point of orientation for scientists, that aim to utilize these molecules in materials, nanotechnological, and biomedical applications.


GENERAL INFORMATION
All chemicals were purchased from Sigma-Aldrich and used without any further purification. Solvents were distilled prior to usage. Dichloromethane and chloroform were neutralized with K2CO3 before distillation. Thin layer chromatography (TLC) was performed on Merck silica gel 60 F524, detected by UV-light (254nm, 366nm). Column chromatography was performed on Macherey-Nagel silica gel 60 M (230-400 mesh, 0.04-0.063 mm). NMR spectroscopy was performed on a Bruker Avance Neo CryoProbe DCH ( 1 H: 600 MHz, 13  MHz, 13 C: 100 MHz). Deuterated solvents were purchased from Sigma Aldrich and used as received. 1 H NMR and 13 C NMR chemical shifts d are given in parts per million [ppm] and are referenced to residual protic impurities in the solvent ( 1 H NMR), or to the deuterated solvent itself ( 13 C NMR). The resonance multiplicities are indicated as "s" (singlet), "d" (doublet), "t" (triplet), "q" (quartet) and "m" (multiplet). Signals referred to as "bs" (broad singlet) are not clearly resolved or significantly broadened.
The crystal was kept at a steady T = 153 K or 173 K during data collection. The structure was solved with the ShelXS 2014/4 solution program using direct methods and by using Olex2 as the graphical interface. The model was refined with ShelXL 2018/3 using full matrix least squares minimization on F 2 . [1][2][3][4][5] IR spectroscopy was performed on a Bruker FT-IR Tensor 27 and Pike MIRacle ATR unit. The ATR unit was equipped with a diamond crystal plate and high-pressure clamp. Spectra were recorded as solid samples directly from the diamond crystal. All absorptions ṽ are given in wave numbers [cm -1 ]. UV/vis spectroscopy was carried out on a Varian Cary 5000 UV-Vis-NIR spectrometer. Spectra were recorded at room temperature using quartz cuvettes with a path length of 1 cm. Fluorescence spectra were recorded on a Shimadzu RF-5301PC spectrofluorophotometer. Electrochemical measurements

S3
were conducted in a classical three electrode cell from Deutsche Metrohm GmbH & Co. KG, which was connected to Metrohm Autolab PGSTAT 101, controlled by NOVA 1.6 software, running on a personal computer. As working electrode, a motionless platinum disc electrode (0.07 cm 2 ) was used combined with a platinum wire that served as counter electrode. All potentials are presented relative to an Ag/AgCl (2 M lithium chloride in ethanol) reference electrode with a potential of 0.164 V vs. SHE at 21 ± 1 °C. Spectra were recorded in methylene chloride (HPLC grade) at 21 ± 1 °C with 0.1 M n-Bu 4 NPF 6 as supporting electrolyte. For cyclic voltammetry three different scan rates of ν = 50, 100 and 500 mVs -1 were chosen whereas differential pulse voltammetry was conducted with a scan rate of ν = 1 mVs

4-yl))tetrabenzoporphyrin 31
Purified by filtration over silica gel (CH2Cl2 +1% TFA) and subsequent recrystallization from CH2Cl2/NEt3 with MeOH, 1.04 g, 59% (reaction batch was ½ the size as it is descriped in the general procedure General procedure to meso-tetraaryltetrabenzoporphyrinato-Pd II complexes: PdCl2 (20 eq.) was suspended in PhCN (10 ml) and heated to 108 °C under nitrogen atmosphere. After all inorganics were dissolved, the respective TATBP (50 mg) was added and the mixture was reacted at 180 °C for 1 h. The solvent was removed in vacuo and the residue was purified by plug filtration (silica gel, CH2Cl2). The bright green fraction was concentrated, and the residue precipitated from CH2Cl2 and MeOH.

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X-ray analysis of 23 Single clear greenish yellow plate crystals of 23 crystallized from a mixture of CHCl3/TFA and methanol by solvent layering. The CF3-group of one TFA molecule showed disorder, and was refined to 54 : 46 % occupation. There is a single molecule in the asymmetric unit, which is represented by the reported sum formula. In other words: Z is 2 and Z' is 1.

S29
X-ray analysis of 29 Single clear dark blue octahedral crystals of 29 crystallized from a mixture of CH2Cl2/TFA and methanol by solvent layering. Absolute structure could not be determined reliably (Flack = 0.6).
Therefore, the structure was refined as racemic twin. The Flack parameter was refined to 0.6(8). Determination of absolute structure using Bayesian statistics on Bijvoet differences using the Olex2 results in 0.4 (5). Note: The Flack parameter is used to determine chirality of the crystal studied, the value should be near 0, a value of 1 means that the stereochemistry is wrong, and the model should be inverted. A value of 0.5 means that the crystal consists of a racemic mixture of the two enantiomers. The value of Z' is 0.5. This means that only half of the formula unit is present in the asymmetric unit, with the other half consisting of symmetry equivalent atoms.  Table S1. Crystal data and structure refinement for 2 (17Jux_MR01) and 4 (DL03).

NSD ANALYSIS
For Normal Structural Decomposition (NSD) analyses, we used the NSD engine program as provided by J. A. Shelnutt [7] , which was handed to us by the Senge group from Dublin. The theory and development of this method have been described by Shelnutt and co-workers. [8][9][10] NSD employs the decomposition of the conformation of the porphyrin macrocycle by a basis set composed of its various normal modes of vibration. The result affords the quantitative separation of the contributing distortions to the macrocycle conformation.
The normal-modes for the out-of-plane distortions of the minimum basis consist of the lowest energy vibration from each symmetry and comprise the saddle (B2u), ruffle (B1u), domed (A2u), propellered (A1u) and the degenerate wave modes [Eg(x) and Eg(y)]. The in-plane modes that compose the minimum basis are the meso-stretching (B2g), N-stretching (B1g), pyrrole-translation [Eu(x) and Eu(y)], breathing (A1g) and pyrrole-rotation (A2g). [11,12] Figure S11. Complete NSD analysis 2, 4, 9, 12Pd, 14, 16, 23, 26, 27 and 29.                                                          , where V is the reaction volume (3 cm 3 ) and S the irradiated area of the cell (0.32 cm 2 ). Figure S178. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 2 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 2 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S159 Figure S179. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 3 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 3 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S160 Figure S180. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 4 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 4 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S161 Figure S181. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 10 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 10 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S162 Figure S182. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 15 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 15 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S163 Figure S183. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 16 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 16 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S164 Figure S184. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of 24 (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of 24 was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S165 Figure S185. Singlet oxygen generation monitored by absorption spectroscopy using DPBF as singlet oxygen scavenger in DMF + 1% NEt3. a) spectral changes upon irradiation in the presence of TPP (black line). b) decrease of DPBF absorption maximum at 415 nm after different irradiation periods. The spectrum of TPP was subtracted for clarity. inset: first-order kinetic of photooxidation of DPBF. S166 Figure S186. Photodegradation monitored by UV/vis absorption spectroscopy of DPBF in DMF + 1% NEt3 after different periods of irradiation time. Inset: decrease of the relative intensity of absorption maximum at 415 nm versus irradiation time. . b kb is defined as the slope of the plot ln(A/A0) of the DPBF absorption maximum vs irradiation time. c Drel( 1 O2) is the relative singlet oxygen quantum yield and is defined as Drel( 1 O2) = ∆ 8--9 : ;<;=/ × ∫ 2 ;// 9 :