Bryan Po-Wen Chen

11 Questions 22 Answers 0 Followers

Questions related from Bryan Po-Wen Chen

How to set probe radius of cavity plot in platon to be less than 1 Ang.?

Hi, I have few photochromic powder in crystal, and some of them are photochromic, some are not. I want to correlate the photochromicity with the way of crystal packing. Therefore, I ran a...

10 October 2022 5,209 0 View

How to convert single crystal structure to PXRD spectrum and grab d-spacing in pi-stacking molecules?

I have resolved several aromatic compounds' absolute structures in single-crystal x-ray, and all of them showed cofacial/slipped close-packing/stacking of the aromatic rings. Later, I used VESTA...

06 April 2022 8,651 6 View

Is the single crystal structure .cif file really reflects the actual molecular packing?

I am trying to correlate the IR spectrum and single crystallography data. In single crystal IR spectra, I found some inter-molecular hydrogen bonds were stronger (from wavenumber shift), and I...

07 November 2021 1,686 3 View

How to determine fluorescence quantum yield for photoswitchable/photochromic compounds?

How to determine FQY for photoswitchable compounds? I found most related publications didnt mention, or just said that they used "Absolute quantum yield spectrometer." I think such technique...

01 November 2020 8,125 5 View

Why unrestricted DFT (uB3LYP) leads to an excited state geometry different from restricted one?

# opt TD(singlets,nstates=3) uB3LYP/6-31g(d,p) # opt TD(singlets,nstates=3) B3LYP/6-31g(d,p) ------------------------------------------------------------------------ Im currently trying to...

28 February 2018 9,902 3 View

How do I determine if an intramolecular proton transfer is likely to happen in Gaussian simulation?

I have an azo dye, which I suspect it may form intramolecular hydrogen bond after photoisomerization. The intramolecular hydrogen bond may have faciliated the proton transfer. After...

04 October 2017 2,531 7 View

Which Cp ring of carboxylic ferrocene can undergo eletrophilic addition?

I use carboxylic ferrocene (Fc-COOH) and react with acetic anhydride in H3PO4. Hopefully I can get acetylation on the Cp ring without COOH. But from H NMR, it seems that I got 100% of acetylation...

15 March 2016 7,972 3 View

In an oxidation process by cyclic voltammetry, why did I get less positive peak?

In an oxidation process by cyclic voltammetry, compared to naked ITO electrode, I got less positive peak when ITO was coated with by solid phase catalyst. Do i interpret the less positive peak as...

30 April 2015 715 8 View

Why CdSe, ZnS... are fluorescent while Iron oxide or most semiconductor are not?

I think these materials are semiconductors, but why not all exciton recombinations with respect to different materials all show photons coming, so called quantum dots? Do the efficiencies of...

09 February 2015 5,290 3 View

Why my transparent organic crystal became totally opaque after DCM dried?

I have synthesized a small organic compound and prepared crystal for x-ray single crystal measurement. They were beautifully transparent, and I remove the remaining DCM from vial. After ~30 mins,...

01 January 1970 474 14 View

Why is crystal violet lactone in its acidic form not emitting fluorescence from first excited state?

Crystal violet lactone in acidic condition (opened ring) is deep blue-purple color, resulting from the absorbance around 600 nm. Why is it not emitting fluorescence from this excitation (FL >...

01 January 1970 8,322 4 View