Chemthink is currently not operational.
Chemthink's hosting provider has upgraded its database software and this has caused issues with the code that runs chemthink. I'm working on finding a solution but the code was written 10 years ago and may require a complete rewrite to make it work. If that is the case I will first work to make the site available without the database functionality.
I hope to have an update and time estimate by 8/23/2015.
Sorry for the inconvenience at the start of the school year.