Titanium dioxide, TiO2, is an important photocatalytic material that exists as two main polymorphs, anatase and rutile. The presence of either or both of these phases impacts on the photocatalytic performance of the material. The present work reviews the anatase to rutile phase transformation. The synthesis and properties of anatase and rutile are examined, followed by a discussion of the thermodynamics of the phase transformation and the factors affecting its observation. A comprehensive analysis of the reported effects of dopants on the anatase to rutile phase transformation and the mechanisms by which these effects are brought about is presented in this review, yielding a plot of the cationic radius versus the valence characterised by a distinct boundary between inhibitors and promoters of the phase transformation. Further, the likely effects of dopant elements, including those for which experimental data are unavailable, on the phase transformation are deduced and presented on the basis of this analysis.

https://link.springer.com/content/pdf/10.1007%2Fs10853-010-5113-0.pdf

Review of the anatase to rutile phase transformation

Laboratory scaled flow-through processes have seen an explosive development over the past decade and have become an enabling technology for improving synthetic efficiency through automation and process optimization. Practically, flow devices are a crucial link between bench chemists and process engineers. The present review focuses on two unique aspects of modern flow chemistry where substantial advantages over the corresponding batch processes have become evident. Flow chemistry being one out of several enabling technologies can ideally be combined with other enabling technologies such as energy input. This may be achieved in form of heat to create supercritical conditions. Here, indirect methods such as microwave irradiation and inductive heating have seen widespread applications. Also radiation can efficiently be used to carry out photochemical reactions in a highly practical and scalable manner. A second unique aspect of flow chemistry compared to batch chemistry is associated with the option to carry out multistep synthesis by designing a flow set-up composed of several flow reactors. Besides their role as chemical reactors these can act as elements for purification or solvent switch.

Flow Chemistry – A Key Enabling Technology for (Multistep) Organic Synthesis

This Review describes singlet oxygen (1O2) in the organic synthesis of targets on possible 1O2 biosynthetic routes. The visible-light sensitized production of 1O2 is not only useful for synthesis; it is extremely common in nature. This Review is intended to draw a logical link between flow and batch reactions—a combination that leads to the current state of 1O2 in synthesis.

Using Singlet Oxygen to Synthesize Natural Products and Drugs

Titanium dioxide is one of the most intensely studied oxides due to its interesting electrochemical and photocatalytic properties and it is widely applied, for example in photocatalysis, electrochemical energy storage, in white pigments, as support in catalysis, etc. Common synthesis methods of titanium dioxide typically require a high temperature step to crystallize the amorphous material into one of the polymorphs of titania, e.g. anatase, brookite and rutile, thus resulting in larger particles and mostly non-porous materials. Only recently, low temperature solution-based protocols gave access to crystalline titania with higher degree of control over the formed polymorph and its intra- or interparticle porosity. The present work critically reviews the formation of crystalline nanoscale titania particles via solution-based approaches without thermal treatment, with special focus on the resulting polymorphs, crystal morphology, surface area, and particle dimensions. Special emphasis is given to sol–gel processes via glycolated precursor molecules as well as the miniemulsion technique. The functional properties of these materials and the differences to chemically identical, non-porous materials are illustrated using heterogeneous catalysis and electrochemical energy storage (battery materials) as example.

High surface area crystalline titanium dioxide: potential and limits in electrochemical energy storage and catalysis.

Synthetic photochemistry carried out in classic batch reactors has, for over half a century, proved to be a powerful but under-utilised technique in general organic synthesis. Recent developments in flow photochemistry have the potential to allow this technique to be applied in a more mainstream setting. This review highlights the use of flow reactors in organic photochemistry, allowing a comparison of the various reactor types to be made.

https://www.beilstein-journals.org/bjoc/content/pdf/1860-5397-8-229.pdf

Flow photochemistry: Old light through new windows

Preparation and characterisation of titanium dioxide films for catalytic applications generated by anodic spark deposition

Die Miniaturisierung von Reaktoren hat eine bemerkenswerte Eigendynamik entwickelt. Die Schwierigkeit besteht dabei oft darin, in das Konzept analytische Komponenten oder Einrichtungen zum Energieeintrag etc. zu integrieren. Fur den Fall der Photomikrostrukturreaktoren ist es nun gelungen, Leuchtdioden (LEDs) als Lichtquellen mit dieser Reaktortechnik zu kombinieren. Daruber hinaus wird die Eignung von LEDs als monochromatische Lichtquelle im chemischen Labor gezeigt.

Leuchtdioden in der Chemie – Eine Hochzeit verschiedener Technologien

Durch Reaktion von Trimesitylvanadium mit Lithiumorganylen, LiR (R = Ph, o-Tol, Dmop, Me, CPh3)1 , sind Complexe des Typs Li(thf)4 VMes3R zuganglich. Mit geeigneten Dilithiumverbindungen konnen auch verbruckte Zweiternvanadate wie Li2(thf)8V2-(μ-C6H4)Mes6 und Li2(thf)8V2(μ-C2)Mes6 erhalten werden. Die thermischen, magnetischen und spektralen Eigenschaften dieser neuen Verbindungen werden untersucht.



Arylvanadium (III) Compounds. VI. Preparation and Properties of Lithium Trimesityl organyl Vanadates



Trimesityl vanadium reacts with LiR (R = Ph, o-Tol, Dmop, CH3, CPh3) forming complexes Li(thf)4 VMes3R. With Li2C6H4 and Li2C2 the compounds Li2(thf) 8 V(μ-C6H4)Mes6 and Li2(thf)8V(μ-C2)Mes6 are obtained. All compounds are characterized by their thermal, magnetical, and spectral properties.

Arylvanadium(III)‐Verbindungen. VI. Darstellung und Eigenschaften von Lithium‐trimesityl‐organyl‐vanadaten(III)

Structural, photophysical and -chemical characterisation and reactivity of a novel polypyridyl
ruthenium complex based on 3,5,6,8-tetra-bromophenanthroline are discussed.
Signal storage at a molecular level is great challenge for chemistry.1 The possibility of
connecting different functionalities selectively to one ligand of a metal complex may open the
route towards higher integrated molecular units capable of processing various external stimuli
in a predesignated order. The implementation of this concept demands ligands with a
multitude of potential connecting groups which can selectively be transformed.2 3-bromo- and
3,8-dibromophenanthrolines have proved useful for the preparation of mononuclear3 and
multiheteronuclear complexes.4 These systems have found applications ranging from DNA
photoprobes5 to metalloligands in catalysis.6 A very useful feature of this
bromophenanthroline ruthenium complexes is their susceptibility towards nucleophilic
aromatic substitution which is very well established.

/pdf/regioselective-functionalization-of-tetrabromophenanthroline-5ecr27526v.pdf

Regioselective Functionalization of Tetrabromophenanthroline−Ruthenium Complexes

Lithium-2,6-dimethoxyphenyl reagiert mit Vanadocen zu Li2V(Dmop)4. Ein entsprechender Vanadium(III)-Komplex LiV(Dmop)4 wird aus VBr3(thf)3 in Benzol erhalten. Beide Verbindungen bilden bei Ligandenabspaltung das dimere [V(Dmop)2]2. Fur analytische Zwecke wurde Hg(Dmop)Cl hergestellt.



Arylvanadium(III) Compounds. V. Formation of Vanadium Complexes with 2,6-Dimethoxyphenyl



Lithium 2,6-dimethoxyphenyl reacts with vanadocene forming Li2V(Dmop)4. With VBr3(thf)3 the vanadium(III) compound LiV(Dmop)4 is obtained. Both complexes decompose by ligand abstraction yielding [V(Dmop)2]2. For analytical purposes Hg(Dmop)Cl was synthesized.

Günter Kreisel

Papers

Preparation and characterisation of titanium dioxide films for catalytic applications generated by anodic spark deposition

Leuchtdioden in der Chemie – Eine Hochzeit verschiedener Technologien

Arylvanadium(III)‐Verbindungen. VI. Darstellung und Eigenschaften von Lithium‐trimesityl‐organyl‐vanadaten(III)

Regioselective Functionalization of Tetrabromophenanthroline−Ruthenium Complexes

Arylvanadium(III)‐Verbindungen. V. Zur Bildung von 2,6‐Dimethoxyphenylverbindungen des Vanadiums