Process for the synthesis of symmetric and unsymmetric oxygen bridged dimers of boron subphthalocyanines (µ-oxo-(BsubPc)2s).

A process for the gram scale synthesis of the oxygen bridged dimer of boron subphthalocyanine, µ-oxo-(BsubPc)2, has been developed. During the development it was found that a wide range of reaction pathways under diverse conditions lead to µ-oxo-(BsubPc)2 formation. However, obtaining µ-oxo-(BsubPc)2 as the main reaction product in appreciable yields and its subsequent isolation were extremely challenging. The best balance of purity, yield and conversion was achieved with a time controlled reaction of an equimolar reaction of HO-BsubPc with Br-BsubPc in the presence of K3PO4. The purification involved sequentially Soxhlet extraction, Kauffman column chromatography and train sublimation. We have repeated the process and yields ranged from 27 to 30% of pure, doubly-sublimed µ-oxo-(BsubPc)2. This process also enabled the synthesis of unsymmetric µ-oxo-(BsubPc)2s by reaction of HO-BsubPc with Br-F12BsubPc, Cl-Cl6BsubPc and Cl-Cl12BsubPc. After synthesis the solution-state properties of the unsymmetric µ-oxo-(BsubPc)2s were investigated, and compared to the symmetric µ-oxo-(BsubPc)2 and more broadly to other BsubPcs. The electronic properties of µ-oxo-(BsubPc)2 were found to differ from its unsymmetric counterparts, but were found to be similar to halo-BsubPcs. Furthermore, the photophysical properties of µ-oxo-(BsubPc)2, both symmetric and unsymmetric, differed greatly from all other known BsubPcs.

Modulation of reactive oxygen species photogeneration of bacteriopheophorbide a derivatives by exocyclic E-ring opening and charge modifications.

With the knowledge that the dominant photodynamic therapy (PDT) mechanism of 1a (WST09) switched from type 2 to type 1 for 1b (WST11) upon taurine-driven E-ring opening, we hypothesized that taurine-driven E-ring opening of bacteriochlorophyll derivatives and net-charge variations would modulate reactive oxygen species (ROS) photogeneration. Eight bacteriochlorophyll a derivatives were synthesized with varying charges that either contained the E ring (2a-5a) or were synthesized by taurine-driven E-ring opening (2b-5b). Time-dependent density functional theory (TDDFT) modeling showed that all derivatives would be type 2 PDT-active, and ROS-activated fluorescent probes were used to investigate the photogeneration of a combination of type 1 and type 2 PDT ROS in organic- and aqueous-based solutions. These investigations validated our predictive modeling calculations and showed that taurine-driven E-ring opening and increasing negative charge generally enhanced ROS photogeneration in aqueous solutions. We propose that these structure-activity relationships may provide simple strategies for designing bacteriochlorins that efficiently generate ROS upon photoirradiation.

Sulfonate pseudohalides of boron subphthalocyanine.

The crystal structures of three sulfonate pseudohalide derivatives of boron subphthalocyanine (BsubPc) are described and compared with four structures of three published sulfonate derivatives. Benzenesulfonate boron subphthalocyanine [(benzenesulfonato)(subphthalocyaninato)boron, C(30)H(17)BN(6)O(3)S, (I)] crystallizes in the space group P-1 with Z = 2. The structure contains two centrosymmetric π-stacking interactions between the concave faces of the isoindoline units in the BsubPc ligands. 3-Nitrobenzenesulfonate boron subphthalocyanine [(3-nitrobenzenesulfonato)(subphthalocyaninato)boron, C(30)H(16)BN(7)O(5)S, (II)] crystallizes in the space group P2(1)/c with Z = 4. The structure contains an intermolecular S-O···π interaction from the sulfonate group to a five-membered N-containing ring of an isoindoline unit on the concave side of a neighbouring BsubPc ligand, at a distance of 3.151 (3) Å. The crystal of methanesulfonate boron subphthalocyanine [(methanesulfonato)(subphthalocyaninato)boron, C(25)H(15)BN(6)O(3)S, (III)] was produced via sublimation and it is not a solvate, in contrast with two previously published structures of the same compound. Compound (III) crystallizes in the space group P2(1)/n with Z = 2, and its structure is similar to that of the more common compound Cl-BsubPc.

Pseudohalides of boron subphthalocyanine.

The synthesis and study of a series of pseudohalides of boron subphthalocyanine (BsubPc) are reported. Each pseudohalide has been compared to the more common chloride and bromide of BsubPc, and we have found that most react slower under standard phenoxylation and hydrolysis conditions. Three pseudohalides (TsO-BsubPc, MsO-BsubPc, and BsO-BsubPc) do not hydrolyze at all even after prolonged periods of time in the presence of water. Single crystals of TsO-, MsO-, and ClsO-BsubPc were obtained, and their structures were unambiguously determined.

(4-Cyano-phenolato)(subphthalocyaninato)boron.

The crystal structure of the title compound, C(31)H(16)BN(7)O, (CNPhO-BsubPc) is characterized by pairs of π-π stacking inter-actions between the concave faces of inversion-related BsubPc fragments with a centroid-centroid distance of 3.600 (1) Å. In addition, these pairs of mol-ecules are linked into chains along [101] through further weak π-π stacking inter-actions with a centroid-centroid distance of 3.8587 (9) Å. There are also weak C-H⋯π(arene) inter-actions within the chains.

Chloro boron subphthalocyanine and its derivatives: dyes, pigments or somewhere in between?

Nine derivatives of chloro boron subphthalocyanine (Cl-BsubPc, 1) have been synthesized and characterized. Seven dimers of Cl-BsubPc have been synthesized by reaction with biphenol (2a), bisphenol A (2b), bisphenol F (2c), bisphenol O (2d), bisphenol P (2e), bisphenol S (2f) and bisphenol Z (2g). For comparison two monomeric phenoxy- (3a) and 4-methylphenoxy (3b) BsubPcs have also been synthesized. Crystals were grown for dimer 2c, whereas all attempts to grow crystals of the remaining dimers resulted in the formation of molecular glasses or amorphous precipitates. Analysis on the structure of 2c suggests that the rigidity and aromatic nature of the central bisphenolic directs the crystal packing. The solubility of the BsubPc dimers in a variety of common organic solvents was measured and compared to that of Cl-BsubPc (2) and monomers 3a and 3b. We have defined ranges for classifying BsubPc derivatives based on their solubility in these solvents: pigment < or = 1 x 10(-8) M, 1 x 10(-3) M < or = pigment-like > 1 x 10(-8) M, 1 x 10(-2) M < or = dye-like > 1 x 10(-3) M, and dye > 1 x 10(-2) M. From this Cl-BsubPc (1) and compounds 2a, 2b, 2c, 2e and 2g are pigment-like while compounds 2d, 2f, 3a and 3b are dye-like. None are exclusively pigments or dyes. In this first approximation of this dye versus pigment classification we have not considered other processes besides solvation which could be undesirable such as polymorphic changes or Ostwald ripening. We have concluded that derivatization of Cl-BsubPc (1) with bisphenols and phenols can be used to control the solubility of BsubPc derivatives. We have also concluded that Cl-BsubPc (1) should not be considered a dye rather is pigment-like in its solubility.

(4-Nitro-phenolato)(subphthalo-cyaninato)boron(III).

The main feature of the structure of the title compound, C(30)H(16)BN(7)O(3) or NO(2)PhO-BsubPc, are pairs of mol-ecules linked through π-inter-actions between the concave faces of the BsubPc fragments at a distance of 3.5430 (11) Šacross an inversion centre. However, the angle between the planes of the five- and six-menbered rings involved in this inter-action is 1.44 (10)°, causing the inter-acting BsubPcs units to be slightly askew rather than parallel as is typical for π-stacking inter-actions.

(Dodecafluorosubphthalocyaninato)(4-methylphenolato)boron(III).

In the title compound, C(31)H(7)BF(12)N(6)O, mol-ecules are arranged into one-dimensional columns with an inter-molecular B⋯B distance of 5.3176 (8) Å. Bowl-shaped mol-ecules are arranged within the columns in a concave bowl-to-ligand arrangement separated by a ring centroid distance of 3.532 (2) Šbetween the benzene ring of the 4-methyl-phen-oxy ligand and one of the three five-membered rings of a symmetry-related mol-ecule.

(4-Acetyl-phenolato)(subphthalo-cyaninato)boron(III).

In the title compound, C(32)H(19)BN(6)O(2), the B atom adopts a BON(3) tetra-hedral coordination geometry. In the crystal, pairs of mol-ecules are associated through aromatic π-π stacking inter-actions between the concave faces of the boronsubphthalocyanine fragments at a centroid-centroid distance of 3.4951 (19) Šand a weaker inter-action of the same type between the convex faces of the same group [centroid-centroid separation = 3.5669 (18) Å] also occurs.