Crystallization for Polarized Light Microscopy

I have a passion for microscope, and have over the years started to improve my setup to allow me to capture all manner of things. The most recent addition (June 2016) was the purchase of a polarizing retrofit kit for my Radical RXL-4T Microscope and my Nikon DSLR.

A polarizing microscope is an often undervalued tool which allows the microscopist to control which light reaches the objective based on the polarization of the light. One of the great features of Polarized Light Microscopy is the fantastic color that arises from a number of ‘optically active’ samples as a result of double-refraction or Birefringence . This double-refraction occurs because materials in a molecularity ordered compound can be either Isotropic (the index of refraction is equal in all directions) or they can be anisotropy (the spatial distribution of properties is non-uniform, e.g. refraction), it is the non-uniform refraction that creates the fascinating colors.

Whilst I have some chemistry background through university, I am far more biologically inclined so this article is designed to share some of the findings I had around which organic and inorganic materials formed crystals or optically active lattices. Over time I will aim to update this article with links to individual chemicals which had an interesting crystal structure or that were optically active and write-ups on each.

 

It should be noted that the following experiments were conducted in a chemistry laboratory, with appropriate PPE. Because most if not all of these chemicals are considered toxic, the following should not be repeated except in a controlled and safe environment.

 

In most cases, I have dissolved the respective chemical in either water or a specific solvent, placed this directly on a microscope slide and through heating attempted to remove the solvent…

ChemicalNotes
Calcium CarbonateDid not form crystals
Potassium PermanganateFormed crystals
Copper AcetateFormed crystals
Stannus ChlorideFormed crystals
L-Glutamic AcidFormed tree like crystals
StarchFormed bubbles
Sulfur in Carbon DisulphideFormed crystals
MannitolFormed crystals
Magnesium ChlorideDid not form crystals
Potassium CarbonateFormed small crystals
Magnesium SulphideFormed crystals
Citric AcidFormed crystals
Monosodium GlutamateDid not form crystals
D-FructoseDid not dry under heat
ALS FerricFormed crystals
Copper SulfideFormed some crystals
FructoseDid not dry under heat
QuinolFormed crystals
Vitamin B6Formed crystals
Aluminium ChlorideFormed crystals
L-AlinineFormed crystals
Sodium CarbonateFormed crystals
Boric AcidDid not form crystals
Sorbic AcidFormed crystals
Vitamin B (Palminate)Did not form crystals
Tin ChlorideFormed crystals
Lithium ChlorideDid not form crystals
Lactic AcidDid not form crystals
AcetamideDid not form crystals
Vitamin E AcetateDid not form crystals, did not dry at temperature
IodineFormed crystals
Sodium PersulphateFormed crystals
Vitimin A AcetateDid not form crystals
Caffeine in MethanolFormed crystals