In Situ Studies on Phase Transitions of Tris(acetylacetonato)-Aluminum(III) Al(acac)3

Abstract

Abstract:In situ investigations on the nucleation and crystallization processes are essential for understanding of the formation of solids. Hence, the results of such experiments are prerequisites for the rational synthesis of solid materials. The in situ approach allows the detection of precursors, intermediates, and/or polymorphs, which are mainly missed in applying ex situ experiments. With a newly developed crystallization cell, simultaneous in situ experiments with X-ray diffraction (XRD) and luminescence analysis are possible, also monitoring several other reaction parameters. Here, the crystallization of the model system tris(acetylacetonato)-aluminum(III) Al(acac) 3 was investigated.In the time-resolved in situ XRD patterns, two polymorphs of Al(acac) 3 , the α-and the γ-phase, were detected at room temperature and the influence of the pH value onto the product formation was studied. Moreover, changes in the emission of Al(acac) 3 and the light transmission of the solution facilitated monitoring the reaction by in situ luminescence. The first results demonstrate the potential of the cell to be advantageous for controlling and monitoring several reaction parameters during the crystallization process.

In situ luminescence analysis: a new light on monitoring calcium phosphate phase transitions

“…S6B ‡), while in situ measurements locate this phase transition at t = 13 min. As observed in our previous work, 45 the sample preparation conditions can lead to the ex situ conversion of the phase mixture to the stable CaHPO 4 ·2H 2 O compound. Within the in situ luminescence measurements, the Ce 3+ emission intensity remains approximately constant at t = 20-40 min, indicating no significant structural change in this time range, in agreement with the respective ex situ XRD patterns (Fig.…”

“…The formation of solid material at t = 0.5 min is detected by the strong decrease of the intensity of the light source, caused by the increase of the turbidity of the solution, blocking light transmission. 45 The light transmission decreases further up to t ≈ 14 min, during the formation of CaHPO 4 ·2H 2 O (Fig. 5), and is rather constant while the growth of CaHPO 4 ·2H 2 O stabilizes.…”

In situ Monitoring of the Formation of [Bis(acetylacetonato)manganese(II)] Complexes

“…The in situ XRD experiments were carried out at the PETRA III beamlines P02.1 (60 keV, λ = 0.2066 Å) and P08 (25 keV, λ = 0.4959 Å) at Deutsches Elektronen‐Synchrotron DESY in Hamburg, applying an especially designed reactor holder (Figures S7 and S8, Supporting Information). This reactor holder was equipped with an inclusive heating and stirring systems as well as additional openings for the passage of the synchrotron X‐ray beam . The applied glass reactor included an additional indented glass tube for decreasing the reaction volume penetrated by the beam for decreasing the background of the in situ PXRD measurements .…”

“…This reactor holder was equipped with an inclusive heating and stirring systems as well as additional openings for the passage of the synchrotron X‐ray beam . The applied glass reactor included an additional indented glass tube for decreasing the reaction volume penetrated by the beam for decreasing the background of the in situ PXRD measurements . The scattered signals were collected at DESY with a Perkin–Elmer XRD1621 detector (Perkin–Elmer Technologies, Walluf, Germany) (2048 × 2048 pixels, X pixel size 200.00 mm, Y pixel size 200.00 mm) with a measurement time of 30 s per diffractogram.…”

“…PXRD can also benefit from the high intensity, brilliance and energy of synchrotron radiation, as well as the quality of the available detector systems, which allows high‐quality diffraction patterns to be collected, with high time‐resolution (time scales up to a few seconds) in complicated reactor setups. For such in situ experiments, our setup was modified, tested and successfully applied at synchrotron radiation facilities , …”