You will arrive at the EuroAirport, Basel-Mulhouse-Freiburg. Be sure to take the exit to Switzerland (there is also an exit to France). Take bus No. 50 to the Kannenfeldplatz. Either change to the Bus No. 36 or 38 direction Schifflände to the station Metzerstrasse (only one station) or you walk down the Metzerstrasse and turn left to Klingelbergstrasse; you will reach the Physical Chemistry (picture). Alternatively, follow St. Johanns-Ring (the crossing with the traffic light) for another 100 m to reach the Organic Chemistry (picture) on the right. The Inorganic Chemistry (picture) is nearby; take a look at the site map.

You definitely want to look at the route map (PDF).

Of course you can spend about 25 Swiss francs to get a taxi cab that will bring you directly from the airport to the Institutes.