Transition metal oxide adducts for regulated generation of reactive oxygen species

Field of Invention

The invention relates to the field of transition metal oxide adducts and in particular to such adducts capable of producing reactive oxygen species (ROS) in a controlled manner.

Definitions

Adduct: A product of intermolecular non-covalent polar interaction, yielding compounds with unique physical and chemical properties. Adduct formation often takes place between Lewis acids and Lewis bases. Non-covalent interactions comprise hydrogen bonding, ionic interaction, van der Waals interaction and p-interaction.

Non-covalent bond: A specific type of bond that is mostly hydrogen bonds of various strength and length dictated by non-covalent polar interaction.

Hydrogen bond: Hydrogen bond is a complex conglomerate of at least four intramolecular component interaction types: electrostatic tendency, polar interaction tendency, van der Waals (dispersion/ repulsion) and tendency of charge transfer.

Cocrystal: A product of intermolecular non-covalent polar interaction, with compounds forming a crystalline single-phase complex with unique physical and chemical properties. Non-covalent interactions comprise hydrogen bonding, ionic interaction other than ionic bonds, polar interaction, van der Waals interaction and p-interaction.

Coformers: Chemical atoms, ions and molecular components that participate in the formation of an adduct are coformers. In the context of this invention, coformers are oxidizers, Reactive Oxygen Species modulators, and surfactants.

Complex: A general term to indicate any of the terms cocrystal, adduct, or combination of coformers.

Mono-adduct: A complex of transition metal oxide and one coformer.

Multi-adduct: The multi-adduct is a complex of a transition metal oxide with more than one coformers, or a complex of at least two transition metals in an oxide with at least one coformer. A multi-adduct may be e.g. a binary, tertiary or quaternary or ternary adduct. A binary adduct is a complex of transition metal oxide and two coformers; a tertiary adduct is a complex of transition metal oxide and three coformers; and a quaternary adduct is a complex of transition metal oxide and four coformers. Ternary oxide adduct is two or more transition metals in an oxide that forms an adduct with one or more coformers. Reactive Oxygen Species (ROS): Chemically reactive species of oxygen. Examples include peroxides (H ₂ O ₂ ), superoxide (*0 ² ), hydroxyl radical (*OH), singlet oxygen (0=0 also written as ^x [02] or ^x 02), and alpha-oxygen (a-O).

AO: amine oxide, herein one such example is lauryl amine oxide.

Free radical: A free radical species is an ion that has an unpaired valence electron.

MB: Methylene blue

Background of the Invention

Transition metal oxide nanoparticles have applications in a wide range of fields, due to their tunable chemical and physical properties. Exemplary applications are found in the fields of e.g., microelectronics, energy storage, dye sensitization, solar cells, sensors, biomedicine, biomedical antimicrobial wound-dressings, bactericidal textiles (Guo et al 2015).

Said applications depend on the semiconductor properties of transition metal oxides. The photons from the typical ultraviolet region cause excitation of valence band electrons, for these to move to the conduction band. Consequently, electron and hole are generated, which tend to move towards the surface of the nanoparticle from inside and create reactive oxygen species (ROS) upon reaction with water and oxygen. The band gap and electronic structure of these oxides can be controlled by size and dimensions of the nanoparticle.

Reactive oxygen species (ROS) is the basis of many chemical and biochemical reactions. Nosaka (2017) noted the importance of ROS in the field of biology. Efficient generation of ROS is described as still being a challenge for oxidation processes used in e.g., waste water treatment. A reaction product based on an oxidative reaction benefits from a higher ROS generation rate. An increased ROS generation rate may be accomplished by adding certain chemicals that enhance ROS generation (for example, H ₂ O ₂ ). However, higher ROS generation is actually commonly undesirable for biological reactions, due to the oxidative damages caused to proteins, lipids, and DNA of living organisms. This may in turn lead to aging, necrosis and apoptotic death.

ROS possess multiple functions in cellular biology, with ROS generation a key factor in modulation of cellular signaling involved in cell death, proliferation, and differentiation. Modulation and characterization of transition metal oxide nanoparticle (NP)-induced ROS production are promising in the application of metallic NPs in the areas of regenerative medicine and medical devices (Ahmed et al 2017).

Alexander L. Huang, Gin Wu (CA2754226C) have used reactive oxygen species for treatment of inflammation, by way of causing local, enhanced oxidation or crosslinking of proteins, etc. This was achieved by using an organic oxidizer composition generating reactive oxygen species, at target sites.

During normal metabolism, tissues such as brain, heart and muscles produce harmful ROS and various free radicals (Halliwell, B. and Gutteridge, J. M. C., eds. Free Radicals in Biology and Medicine, (Oxford: Clarendon Press, 1989)). Abnormally high ROS levels have been reported during a brain stroke or myocardial infarction. Walton, M. et al., Brain Res. Rev., 29: 137-168 (1999); Lucchesi, B. R, Am. J. Cardiol., 65:141-231 (1990).

ROS are key to cell signaling pathways and regulation of transformation, proliferation, angiogenesis, and metastasis. Paradoxically, ROS can also suppress tumor progression, and most chemotherapeutic and radiotherapeutic agents work by augmenting ROS stress in cancer cells. Due to the dual role of ROS, both pro-oxidant and antioxidant-based anticancer agents have been developed involving ROS in specific applications (Adams et al 2013).

Since, the generation and concentration of ROS is highly unpredictable due to transition metal oxide crystal type, size, surface, type of coformers, doping, methods of preparation etc. it is not possible to achieve desirable ROS concentration in a specified time for multiple types of potential applications.

Nosaka et. al. 2017 reviewed the photocatalytic generation of ROS by titanium dioxide. The yield of ROS was found to be very low (page 11311, 11315). Apparently, the quantum yield of ROS depends on other atoms and ions doped into the TiO ₂ product. Low quantum yield diminishes the catalytic effect. Electron and hole very often recombine, whereby the efficiency of photocatalysis and ROS generation within the TiO ₂ nanoparticle is reduced.

ROS generation by Tίq2-H2q2 was reported at the catalyst surface by Wiedmar et al, 2016. Non- irradiated such systems using low concentrations of hydrogen peroxide have potential use in dye removal applications using ROS generation, where irradiation may not be feasible. Moreover, Weidmer observed that non-irradiated Tίq2-H2q2 suspensions were significantly more effective in degrading methylene blue, as compared to hydrogen peroxide alone. This indicates that more ROS are created by Tίq2-H2q2 as compared to the individual compounds. However, H ₂ O ₂ started acting on TiO ₂ to generate ROS as soon as it was added to TiO ₂ and the oxidative effect is short-lived.

Non-irradiated systems are also slower than irradiated systems, and therefore at a low H ₂ O ₂ concentration the process of dye removal is even slower. This is in contrast to the commonly desired rapid degradation of the dye molecule.

As has been described, there are many uses for ROS. However, the catalysts used for ROS generation, transition metal oxides such as TiO ₂ or TiO ₂ adducts, are usually photocatalysts, which means that they have limited efficacy under non-illuminated conditions. Slow reaction rates of ROS generation, too fast ROS generation, and generation of ROS at an undesirable location are further problems.

ROS generation in the dark is also desirable, since lack of illumination is limiting to many applications. The photocatalytic ROS generation effect of TiO ₂ however is usually slow. It takes a minimum of 2 to 24 hours to achieve the desirable effect, e.g., a bleaching or germicidal effect.

It is therefore highly desirable to regulate/ control, and possibly enhance ROS generation and concentration by transition metal oxide based photocatalytic product. Hence, there is a need for improved ROS generating adducts providing regulated production of ROS.

Short Description of the Invention

The transition metal oxide adduct according to the invention is capable of producing ROS in a regulated, i.e. controlled manner. While high ROS generation may be desirable for certain reactions, it may be undesirable for other applications that need sustained lower concentrations of ROS over an extended period of time.

The invention relates to a transition metal oxide adduct, which generates ROS through a catalytic reaction of the transition metal oxide nanoparticle or microparticle.

As disclosed herein, “oxide”, in the respective context and depending on the transition metal, includes any of a monoxide, dioxide, trioxide, quaternary oxide, penta oxide or a ternary oxide.

In one embodiment, the transition metal of the transition metal oxide adduct is titanium dioxide.

Disclosed herein, and claimed, is a transition metal oxide adduct, constituting a microparticle or a nanoparticle and comprising

- a) An oxidizer selected from the group comprising or consisting of peroxides, percarbonates, perborates, and persulfates;

- b) A Reactive Oxygen Species (ROS) modulator;

- c) An amine oxide surfactant.

The transition metal of the transition metal oxide adduct has been chosen from the group comprising but not limited to, or consisting of titanium, vanadium, manganese, iron, cobalt, nickel, copper, zinc, platinum, silver, gold.

The oxidizer may comprise or consist of one or more of hydrogen peroxide (H ₂ O ₂ ), sodium percarbonate, sodium perborate, ammonium percarbonate, urea peroxide, sodium persulfate, potassium persulfate, potassium peroxy monosulfate, ammonium persulfate, peroxymonosulfuric acid (Caro's acid), peroxydisulfuric acid, methyl ethyl ketone peroxide, ethyl methyl ketone peroxide, methyl isobutyl ketone peroxide, an aromatic peroxide, tert-Butyl hydroperoxide benzoyl peroxide, dibenzoyl peroxide, di-(l-naphthoyl)peroxide, polyvinylpyrrolidone hydrogen peroxide.

The concentration of the oxidizer is from 0.01% to 10% by weight of the transition metal oxide.

The ROS modulator is a small organic molecule consisting of 1 to 20 carbon atoms chosen from the group comprising or consisting of formic acid, acetic acid propionic acid, benzoic acid, benzyl alcohol, salicylic acid, methanol, ethanol, propanol, esters of small organic acids and alcohols consisting of 1 to 20 carbon atoms. The ROS modulator is present in a concentration from 0.01% to 10% by weight of the transition metal oxide.

The surfactant is an amine oxide. The surfactant comprises or consists of one or more of lauramine oxide, alkyldimethyl amine oxide, cocodimethy lamine oxide, tetradecyldimethyl amine oxide, almondamidopropylamine oxide, behenamine oxide, cocamidopropylamine oxide, cocamine oxide, decylamine oxide, decyltetradecylamine oxide, dihydroxyethyl Cs-is alkoxypropylamine oxide, dihydroxyethyl cocamine oxide, dihydroxyethyl lauramine oxide, dihydroxyethyl stearamine oxide, dihydroxyethyl tallowamine oxide, hydrogenated palm kernel amine oxide, hydrogenated tallowamine oxide, hydroxyethyl hydroxypropyl Cs-is alkoxypropylamine oxide, Isophorone diisocyanate (IPDI)/ PEG-15 soyamine oxide, copolymerisostearamidopropylamine oxide, lauramidopropylamine oxide, lauramine oxide, milkamidopropyl amine oxide, minkamidopropylamine oxide, myristamido-propylamine oxide, myristamine oxide, myristyl/cetyl amine oxide, oleamidopropylamine oxide, oleamine oxide, olivamidopropy lamine oxide, palmitamidopropylamine oxide, palmitamine oxide, PEG-3 lauramine oxide, potassium dihydroxyethyl cocamine oxide phosphate, potassium trisphosphonomethy lamine oxide, sesamidopropylamine oxide, soyamidopropy lamine oxide, stearamidopropylamine oxide, stearamine oxide, tallowamidopropylamine oxide, trimethylamine oxide, undecylenamidopropyla mine oxide, wheat germ amidopropylamine oxide.

The concentration of the surfactant is from 0.01% to 10% by weight of the transition metal oxide

The microparticle or nanoparticle of the invention has a size from 1 to 1000 nm, preferably from 5 to 1000 nm, or from 20 to 100 nm.

Also claimed is a combination of two different transition metal oxide adducts, each having the constituent parts in accordance with the invention as defined herein, wherein the transition metal(s) of the first transition metal adduct are not the same as the transition metal(s) of the second transition metal adduct.

In said combination of two different transition metal oxide adducts, the concentration of the transition metal(s) of the second transition metal adduct may be from 1 part per billion to 1 part per million, by weight of the metal oxide(s) of the first adduct.

The transition metal oxide adduct or combination of two different transition metal oxide adducts may be dissolved in a polar and/or ionic solvent. An example of a polar solvent is water.

In one specific embodiment, wherein the adduct comprises TiO ₂ microparticles or nanoparticles, the adduct concentration, expressed as TiO ₂ content, is less than 1% TiO ₂ by weight, by total volume, e.g. 0.01 to 1%.

In a method according to the invention, ROS generation by the transition metal oxide adduct or adducts is modulated by irradiating said adduct(s) with ultraviolet light.

In a method of manufacturing a transition metal oxide adduct according to the invention, a transition metal oxide microparticle or nanoparticle is co-grinded with one, two or all three of oxidizer, ROS modulator, and surfactant, whereby components not taking part in the co-grinding are added in a subsequent step. Ambient conditions are preferably used.

Short Description of the Figures

Figure 1 shows a labeled diagram of a proposed multi adduct formed either directly on a TiO ₂ or TiO ₂ -peroxy adduct.

Figure 2 shows a labeled diagram of a proposed adduct for photocatalytic activation for reactive oxygen species (ROS) generation.

Figure 3 shows a methylene blue (MB) concentration versus absorbance standard plot.

Figure 4 shows the methylene blue degradation by individual coformers of the adduct.

Figure 5 shows methylene blue degradation by mono adducts of TiO ₂ .

Figure 6 shows methylene blue degradation by mono and binary adducts of TiO ₂

Figure 7 shows methylene blue degradation by mono, tertiary and quaternary adducts of TiO ₂ .

Figure 8 shows methylene blue degradation by zinc oxide adducts.

Figure 9 shows a FTIR spectrum prediction of an (Ti(0H) ₂ -H ₂ 0 ₂ -Silver oxide) adduct.

Figure 10 shows a FTIR spectrum prediction of an (Ti(0H) ₂ -H ₂ 0 ₂ -HC00H) adduct.

Figure 11 shows a FTIR spectrum prediction of an (Ti(0H) ₂ -H ₂ 0 ₂ -HC00H- Silver oxide) adduct.

Figure 12 shows a FTIR spectrum prediction of an (Ti(0H) ₂ -Ha0 ₂ -HC00H- Silver oxide -AO) adduct.

Figure 13 shows a real FTIR spectrum of an (Ti0 ₂ -H ₂ 0 ₂ -HC00H- Silver oxide -AO) adduct.

Detailed description of the Invention

Disclosed herein is a multi-component transition metal oxide adduct constituting a microparticle or nanoparticle and comprising coformers to regulate the ROS generation. Transition metal oxide adducts according to the invention cause the ROS generation either to increase or decrease, as compared to the effect of a neat oxidizer.

The transition metal oxide microparticle or nanoparticle may be in crystalline or amorphous form. The transition metal oxide may be TiO ₂ . Crystalline forms of TiO ₂ nanoparticles can be anatase, rutile or brookite. Doped TiO ₂ constitutes inclusions of other atoms or molecules, e.g. tungsten atoms, within the crystalline TiO ₂ nanocrystals, to enhance the photocatalytic activities. Undoped TiO ₂ , which is used herein in accordance with the invention, means pure TiO ₂ . Other examples of metal oxides are zinc oxide and silver oxide. It should be noted that silver oxide is particularly stable in ambient conditions, unlike many other silver compounds. Silver nitrate is used in the presence of hydrogen peroxide to convert silver nitrate to silver oxide (Firas 2019)., In the examples, silver nitrate is used as a component in sample preparation, to be converted to silver oxide.

Advantageous effects of the adducts are obtained by specific roles of the coformers, as described below.

Oxidizers that are able to form an adduct with e.g. TiO ₂ serve as a depot with ROS -generating capability under dark, non-illuminated conditions. The depot of stabilized oxidizer increases available ROS at any given time point, when ROS generation by TiO ₂ falls short for a given application.

The ROS modulator is a small organic molecule, which inhibits the ROS generation independently of the oxidizer present, under dark or room light conditions. The same small organic molecule shows enhanced ROS generation under ultraviolet light, and may regulate the generation of ROS in a concentration-dependent manner.

The amine oxide surfactant is capable of forming an adduct with TiO ₂ or the oxidizer, with the aim of increasing the effective range of ROS, by reducing the surface tension and increasing the diffusivity of ROS. Thereby, chemical reactions based on ROS may be carried out beyond the immediate vicinity of the TiO ₂ adduct microparticle or nanoparticle. In cases when the ROS penetration is limited by the nonpolar nature of a substrate, the surfactant may solubilize e.g. oils and fats. Thereby, the ROS may either react faster, or overcome barriers of oils and fats.

It should be understood that in the transition metal oxide adduct, each component part still retains its original activity, albeit in modified form. Hence, as part of the adduct, the oxidizer still functions as an oxidizer, the ROS modulator still functions as a ROS modulator, and the surfactant still functions as a surfactant.

Adduct formation is achieved by grinding the metal oxide microparticles or nanoparticles together with either oxidizer, or ROS modulator, or surfactant, preferably under ambient conditions. Alternatively, combinations of two or three or all four of the above components may be co-grinded, again at ambient conditions. Such a method of adduct preparation by grinding is reported earlier in prior art (Rivera 2018, Toda 1987) albeit with different chemicals not same as disclosed in this invention.

Adducts according to the invention are formed by the ROS modulator, together with e.g. TiO ₂ or the Ti0 ₂ -oxidizer adduct, or both of the latter, as an adduct complex. Other examples of metal oxides of the invention are zinc oxide and silver oxide with, TiO ₂ .

One advantage of the adducts of the current invention is storage stability. Co-crystallization reactions, leading to adduct formation, are due to sharing of protons and often accompanied by the transfer of protons from one cocrystal-forming molecule to the other. The result is the formation of a salt. The salt shows improvement of stability, shelf life, solubility, dissolution rate, hydrophobicity-hydrophilicity balance, photon conduction, dielectric properties, increased melting point, and improved compressibility (Cherukuvada 2016 and Delori 2013). Moreover, adducts are novel, nonobvious, and have wide-ranging physiological applications (Cherukuvada 2016).

A further advantage of adduct formation is the reduced environmental impact. The relatively less demanding synthesis procedures of adduct formation, compared with bioorganic synthesis, allows savings of energy, effort, time, and money, and thus provides a greener and more sustainable approach to achieve the functionalities of the adduct of the present invention. The synthetic adduct formation procedures allow the formation of new bonds that alter the physical and chemical characteristics of the participating molecules and adduct complexes.

Transfer or changes in proton sharing by electronegative groups among adduct coformers is the basis of the novel properties of adducts of the present invention.

The formation of new hydrogen bonds or alterations of the exiting hydrogen bonds can be detected by Fourier Transform Infrared Spectroscopy. Alteration in hydrogen bonds influencing semiconductor characteristics can be ascertained using UV-VIS spectroscopy.

Fourier Transform Infrared Spectroscopy results have been predicted using software tools (Schrodinger Maestro), to confirm the adduct formation.

ROS generation and detection

Lee 2015 and Xia 2015 reported degradation of methylene blue (MB) photochemically by generated ROS. The degradation of MB was followed using a UV-Visible spectrophotometer. The mechanism of MB degradation involves ROS-based oxidation.

Examples of oxidizers

Both inorganic and organic peroxides are examples of oxidizers. Suitable water-soluble inorganic oxidizers are selected from peroxides of alkaline earth metals, and include but are not limited to lithium peroxide, potassium peroxide, sodium peroxide, magnesium peroxide, calcium peroxide, barium peroxide, sodium percarbonate, ammonium percarbonate, sodium percarbonate, ammonium percarbonate, urea peroxide, and organic peroxides.

Examples of organic peroxides include but are not limited to polyvinylpyrrolidone hydrogen peroxide, alkyl and/or aryl peroxides (like tert-butyl peroxide, diphenyl peroxide, etc.), alkyl and/or aryl ketone peroxides (like benzoyl peroxide), peroxy esters, diacyl peroxides, peroxy hexonoic acid, peroxide enanthic acid, peroxy caprylic acid, peroxy pelargonic acid, peroxy capric acid, peroxy undecylic acid, peroxy lauric acid, peroxy tridecylic acid, peroxy myristic acid, peroxy palmitic acid, peroxy stearic acid, and alkane peroxides like peroxy formic acid, peroxy acetic acid, peroxy propionic acid and peroxy butyric acid, methyl ethyl ketone peroxide, ethyl methyl ketone peroxide, methyl isobutyl ketone peroxide, and aromatic peroxides like tert- Butyl hydroperoxide benzoyl peroxide, dibenzoyl peroxide, Di-(l-naphthoyl)per oxide. Examples of amine oxides: where Rl, R2, and R3 are saturated or unsaturated and linear or branched alkyl groups of 1-24 carbons; and where aromatic groups may contain O (oxygen) or N (nitrogen) atoms as heterocycles or polyalkoxy groups.

Rl is a saturated or unsaturated chain, preferably of Cs to Cix length.

R2 and R3 are preferably independently selected from Cl to C4, e.g. methyl, ethyl, or 2- hydroxyethyl.

Examples of some amine oxides are lauramine oxide, alkyldimethyl amine oxide, cocodimethy lamine oxide, tetradecyldimethyl amine oxide, almondamidopropylamine oxide, behenamine oxide, cocamidopropylamine oxide, cocamine oxide, decylamine oxide, decyltetradecylamine oxide, dihydroxyethyl Cs-is alkoxypropylamine oxide, dihydroxyethyl cocamine oxide, dihydroxyethyl lauramine oxide, dihydroxyethyl stearamine oxide, dihydroxyethyl tallowamine oxide, hydrogenated palm kernel amine oxide, hydrogenated tallowamine oxide, hydroxyethyl hydroxypropyl Cs-is alkoxypropyl amine oxide, IPDI/ PEG-15 soyamine oxide, copolymer isostearamidopropylamine oxide, lauramidopropylamine oxide, lauramine oxide, milkamidopropyl amine oxide, minkamido-propylamine oxide, myristamido-propylamine oxide, myristamine oxide, myristyl/cetyl amine oxide, oleamidopropy lamine oxide, oleamine oxide, olivamidopropy lamine oxide, palmitamidopropylamine oxide, palmitamine oxide, PEG-3 lauramine oxide, potassium dihydroxyethyl cocamine oxide phosphate, potassium trisphosphonomethy lamine oxide, Sesamidopropy lamine oxide, soyamidopropy lamine oxide, stearamido propylamine oxide, Stearamine oxide, tallowamidopropylamine oxide, trimethylamine oxide, undecylenamidopropylamine oxide, wheat germ amidopropylamine oxide.

The adducts may contain an organic acid. Examples of organic acids include linear or branched alkanes or carboxylic acids, e.g. formic acid, acetic acid, propionic acid, isobutyric acid, benzoic acid, salicylic acid, methanol, ethanol, isopropanol. Combinations of alkanes and/or carboxylic acids may be used.

Example 1

Adduct Preparation Methods:

Raw materials: TiO ₂ Degussa P25, 30% H ₂ O ₂ , 99% HCOOH, 30% Lauramineoxide and Silver Nitrate Powder.

Pre-preparation of Lauramine Oxide:

Lauramine Oxide was treated at 80°C for 24 hrs in a glass vessel. It was then removed and stored in a container. This was used in the adduct preparations below.

Ternary-Adduct 1: Ti(OH)2-H2C>2- Silver oxide adduct

Take in a mortar about 10 gm TiO ₂ .

Add 9.090 mL of 30% Hydrogen Peroxide to it.

Grind well in a mortar pestle until light yellow color sample is obtained.

Add 1 mL of 1000 ppb AgNCh solution. It should be noted that silver nitrate is converted into silver oxide in the presence of H ₂ O ₂ . Therefore, the active adduct component is silver oxide and not silver nitrate.

Grind well in a mortar pestle for about 30 minutes.

Store in a container.

Ternary-Adduct 2: Ti(0H) ₂ -H ₂ 0 ₂ -HC00H adduct

Take in a mortar about 10 gm TiO ₂ .

Add 9.090 mL of 30% Hydrogen Peroxide to it.

Grind well in a mortar pestle until light yellow color sample is obtained.

Add 0.842 mL of 99% Formic Acid.

Do not use a lower concentration of Formic Acid for best results.

Grind well in a mortar pestle for about 30 minutes.

Store in a container.

Quaternary-Adduct 3: Ti(0H) ₂ -H ₂ 0 ₂ --HC00H- Silver oxide adduct

Take in a mortar about 10 gm Multi -Adduct 1 and 10 gm of Multi -Adduct 2.

Grind well in a mortar pestle for about 30 minutes.

It should be noted that silver nitrate is converted into silver oxide in presence of H ₂ O ₂ . Therefore, the active adduct component is silver oxide and not silver nitrate.

Multi Adduct: Ti(OH)2-H2C>2~ HCOOH- AO- Silver oxide adduct

Take in a mortar about 10 gm Multi -Adduct 1 and 10 gm of Multi -Adduct 2.

Grind well in a mortar pestle for about 30 minutes.

Add about 1 gm of heat treated lauramine oxide.

Grind well in a mortar pestle for about 45 minutes.

It should be noted that silver nitrate is converted into silver oxide in presence of H ₂ O ₂ . Therefore, the active adduct component is silver oxide and not silver nitrate. Example 2

Methylene Blue Degradation: As control and experimental method:

Chemical oxidation by reactive oxygen species causes degradation of methylene blue. This reaction can be used to measure ROS generation by the adduct or by its individual components. The following method is used to measure the decrease in methylene blue concentration at a specific wavelength (/unax = 665 nm) over time.

Methylene blue starts to degrade within a few minutes after ROS exposure, which is visually apparent and may be observed using a spectrophotometer at 665 nm (Spekol 1200 of Analytik Jena).

Sample Preparation and procedure for all methylene blue experimental examples Non-Ti02 samples

Stock solutions of 10% Hydrogen Peroxide (H202), 1% Formic Acid (HCOOH), 1% Lauryl Amine Oxide (AO), 1 ppm (or 1000 ppb) Silver Nitrate solutions (Ag) were prepared in advance.

200 pL of 0.96mg/mL methylene blue solution was added to 600 pL of stock solutions.

The volume was adjusted to 6 mL by adding deionized water.

Samples were transferred to a 24 well plate for continuous UV exposure.

For non-UV readings, samples were extracted directly from the tube at various time intervals as described in further examples.

Ti02 samples

Adducts were synthesized by the method in Example 1.

600 pL of 0.96 mg/mL methylene blue (MB) stock was added to 8.4 mL water.

9 mg adduct powder was added to this solution and stirred for 60 minutes in the dark.

After shaking 600 pL of these stock solutions was used for each respective sample, as required.

Final concentrations in test samples were 1 mg/mL Ti02, 1% H202, 0.1% HCOOH and AO and 100 ppb silver nitrate. It should be noted that silver nitrate is converted into silver oxide in presence of H ₂ O ₂ . Therefore, the active adduct component is silver oxide and not silver nitrate.

Each sample was made as a triplicate.

500 pi of the solution was extracted after 0, 15, 30, 60 min for UY-VIS spectrophotometer reading.

The sample was centrifuged at 10000 rpm for 1 min.

The supernatant was transferred to a 1 mm-walled glass cuvette, without disturbing the pellet. From a background study, the methylene blue peak had been found to be at 665 nm. All readings were taken at 665 nm on a Analytik Jena Spekol 1100UV-VIS spectrophotometer.

For samples without Ti02, C/CO has been plotted where CO is the initial concentration of the sample at t=0.

C is the MB concentration in the supernatant at time t.

Methylene Blue degradation (C/Ce) is a measure of ROS generation.

Ce was used in place of CO for samples with Ti02, to account for methylene blue adsorbed onto the Ti02 surface during the adsorption process. At this concentration, adsorption of MB onto Ti02 is very rapid, and therefore the difference in C and CO is immaterial.

Ce or equilibrium adsorption of MB onto Ti02 was calculated using a standard curve of methylene blue concentration vs Absorbance (See Figure 3)

Example 3 Methylene blue (MB) degradation by individual adduct components in the dark:

Reference is made to Figure 4. Samples were prepared as explained in example 2.

Spontaneous degradation of MB in water over time is used as control in this example. Conclusion: Silver, hydrogen peroxide or TiCk alone have considerable effect on ROS generation.

Example 4

Methylene blue degradation by mono and mono adducts of TiO ₂ :

Reference is made to Figure 5. Samples were prepared as explained in example 1.

Conclusions:

The degradation of methylene blue is fastest with mono adduct (TiO ₂ +HCOOH) under ultraviolet light, and slowest for the same combination without UV. Among the samples not being treated with UV light, the degradation of methylene blue is fastest for mono adduct ( TiO ₂ + H ₂ O ₂ .

Example 5

Methylene blue (MB) degradation by mono and binary adducts of Ti02:

Reference is made to Figure 6. Samples were prepared as explained in example Conclusions:

The methylene blue degradation by ( TiO ₂ + H ₂ O ₂ +HCOOH) in ultraviolet light is the fastest, indicating a rapid generation of ROS.

The methylene blue degradation by (TiO ₂ + H ₂ O ₂ + HCOOH) is the slowest, indicating an inhibitory effect of formic acid on ROS generation in the absence of ultraviolet light. This result may be compared with the methylene blue degradation by, respectively, (TiO ₂ +H ₂ O ₂ ) and (TiO ₂ + H ₂ O ₂ + Silver oxide) in the dark or room light.

Effect of Silver

(TiO ₂ +H ₂ O ₂ ) and ( TiO ₂ + H ₂ O ₂ +Silver oxide) generate ROS in the dark room light. Silver oxide acts as a ROS regulator, while HCOOH acts as an ROS inhibitor in the dark.

Example 6

Methylene blue (MB) degradation by mono, tertiary and quaternary adducts of TiO ₂

Reference is made to Figure 7. Samples were prepared as explained in example 1.

Conclusions:

The ROS generation by (TiO ₂ -H ₂ O ₂ ) can be regulated by a small organic molecule. The role of HCOOH, Silver oxide and AO on methylene blue degradation by (TiO ₂ +Th02) in the absence of UV is to inhibitor ROS generation, while in the presence of continuous UV light, ROS formation is enhanced and regulated in a concentration-dependent manner of HCOOH, AO and Silver oxide, individually and as a group, respectively. Example 7

Tabulated results of ROS generation from examples 1 to 5:

Conclusion:

Methylene blue degradation is faster in ultraviolet light in comparison to room light or dark condition.

Small organic molecules regulate ROS generation (i.e. inhibit or enhance ROS generation), depending on ultraviolet light and adduct concentration.

Silver oxide and amine oxide (AO) surfactant also regulate the ROS generation.

Example 8 Methylene blue degradation by zinc oxide adducts:

Reference is made to Figure 8. Samples were prepared as explained in example 2 and adducts were synthesized as per example 1 with the below modifications. T1O ₂ Degussa P25 is replaced by Zinc Oxide powder.

The final concentrations in the test samples were 1 mg/mL ZnO, 1% H ₂ O ₂ , 0.1% HCOOH, 0.1% AO and 100 ppb silver nitrate. It should be noted that silver nitrate is converted into silver oxide in the presence of H ₂ O ₂ . Therefore, the active adduct component is silver oxide and not silver nitrate.

All other parameters and amounts remained identical to Example 2.

Conclusions:

Zinc oxide and its adducts show little or no ROS generation in dark or room light conditions (i.e. without ultraviolet light).

The quaternary adduct of Zinc oxide shows the fastest ROS generation under UV light. The ROS generation by (ZhO-H2q2) can be regulated by a small organic molecule.

ZnO adducts are slower in ROS generation than TiO ₂ adducts.

The respective roles of HCOOH, Silver oxide and AO on methylene blue degradation by (ZnO + H ₂ O ₂ ) in the absence of UV is to inhibit ROS generation. The roles of HCOOH, Silver oxide and AO on methylene blue degradation, in UV, is to enhance the ROS formation and to regulate the ROS generation in a concentration dependent manner, independently and as a group, respectively.

Example 9

Infrared spectra of adducts of the invention:

Infrared spectra of all individual co-formers of the adduct were calculated, and the results are verified with actual values of experimentally synthesize adducts as per the previous examples. The individual co-formers chosen for infrared spectrum determinations are TiO ₂ , H ₂ O ₂ , formic acid (HCOOH), laurylamine oxide (AO) and silver nitrate.

The determinations were made to validate the accuracy of the parameters calculated using software, and the suitability of the set calculated parameters for binary adduct and multi- adduct predictions. The results from predicted calculated spectra, and comparisons with individual adduct coformers and multi-adducts (e.g. binary adducts, ternary adducts) are presented below.

Infrared spectra have been predicted using software-based calculations:

Software: Schrodinger Maestro (2018R1), Jaguar 9.9 TiO ₂ infrared spectrum prediction: A characteristic peak matches with the actual infrared spectrum, thus confirming that the selection of the calculation parameters is accurate. H ₂ O ₂ infrared spectrum prediction: A characteristic peak matches with the actual infrared spectrum, thus confirming that the selection of the calculation parameters is accurate. Laurylamine oxide infrared spectrum prediction: A characteristic peak matches with the actual infrared spectrum, thus confirming that the selection of the calculation parameters is accurate.

Formic acid infrared spectrum prediction: A characteristic peak matches with the actual infrared spectrum, thus confirming that the selection of the calculation parameters is accurate. TiO ₂ - H ₂ O ₂ mono adduct infrared spectrum prediction A molecular structure approximation of the adduct was made. A molecular structure optimization was done and the infrared spectrum calculated. A characteristic peak match with the actual infrared spectrum was observed, thus confirming the selection of the calculation parameters to be accurate.

A unique peak for this adduct is at 1540, 3383, 3461 cm ¹ . This indicates hydrogen bonding and therefore indicates adduct formation interactions between TiO ₂ and H ₂ O ₂ molecules.

3565, 3800 cm-1 indicates -OH stretching at the TiO ₂ surface, while 517, 723 cm ^-1 indicates Ti- O-Ti stretching.

Laurylamine oxide-H2Q2 infrared spectrum prediction

A molecular structure approximation of an adduct was carried out, comprising molecular structure optimization and infrared spectrum calculation. A characteristic peak match with an actual infrared spectrum was observed, thus confirming the selection of the calculation parameters to be accurate.

Enhanced peaks near 3000 cm ^-1 indicate formation of hydrogen bonds in the adduct. The above infrared spectrum prediction of adducts, with matching evidence in the form of experimental values, validates the method of using software-based calculations. Therefore, the same method is used to predict the infrared spectrum of multi-adducts.

A molecular structure approximation of adducts was carried out, comprising molecular structure optimization and infrared spectrum calculation. Reference is made to Figures 8 and 9 for calculated spectrums of multi-adducts. Formation of hydrogen bonds among coformers of the multi-adduct are listed below, along with characteristic spectral wavenumbers.

Conclusions: The peak at 1360/1370 cm ^-1 in the binary adduct of TiO ₂ (Fig 9) shifts to 1345 cm ^-1 in the tertiary adduct (Ti(OH) ₂ -H ₂ 0 ₂ -HC00H-Silver oxide) (Fig 11), due to increased interactions between Silver oxide -TiO ₂ (Ag-O-Ti bonds).

The tertiary adduct ( TiO ₂ H ₂ O ₂ -HCOOFI- Silver oxide) (Fig 11) shows a peak at 1685 cm ^-1 .

A peak at 1365 cm ^-1 is observed for the Silver oxide -TiO ₂ adduct (Figure 9), which is not observed in only TiO ₂ FTIR spectra (Fig 13, TiO ₂ spectrum).

Ti-O-Ti, Ti-O-O and 0-0 bond peak around 500-1000 cm ^-1 (Figs 9, 10).

Figure 10 and Figure 11 show peaks at 1665/ 1685 cm ^-1 , respectively, for shared H of hydrogen bond and -O-C-O deformation of adsorbed formic acid (HCOOH).

Figures 9, 10, 11 and 12 show a simulated peak at about 1070 cm ^-1 , corresponding to titanyl peroxy bonds Ti-O-(OH) ₂ which is present in all adducts disclosed. Figure 12 shows peaks at 1605 cm ¹ for shared H of hydrogen bond and -O-C-O deformation of adsorbed formic acid (HCOOH).

Fig 12 also shows 1330 cm ^-1 for Ti-O-silver oxide bonding.

Fig 12 further shows 2990 cm ^-1 to 3080 cm ^-1 for interactions between hydrophobic tails (C2 and C5) of AO and TiO ₂ .

Shifting of peaks from 1665/ 1685 cm ^-1 (as per figure 10/11) to 1605 cm ^-1 in figure 12 is due to stronger hydrogen bonds in quaternary adducts, in comparison to binary/ ternary adducts in the simulated spectrum.

The above peaks, as predicted by simulated spectra, are also observed in experimental spectra of actual synthesized quaternary adducts (Figure 13), within the limitations of the best approximation of the simulated spectrum calculations.