Jeremy you have an extremely lofty idea here. I'm going to give you advice based on one who has attempted to invest in a distressed area, informally along with other investors, hoping the area would eventually be revitalized. It never happened. I soon learned that in order for a neighborhood to be revitalized, eventually all of the players - residents, businesses and ESPECIALLY the local government - will need to be on board.
IMO, you can tackle this from two angles:
Pull together the local government, businesses and Investors (don't try and go this alone. Share the wealth and work involved. The revilization will be more effective the more diverse the investment.) and draft a plan to bring back the area. You will need the full cooperation of the police department and eventually the residents as you work to rid the area of one of the main factors bringing it down: crime. As crime is being pushed out you will have to work HARD to convince business owners, other investors AND homebuyers and tenants that this is the real deal. The biggest challenge (and this is what I had to learn the hard way) will be to overcome the decades-long stigma that has plagued the neighborhood and get prospective tenants to sign on. Most will only remember how crime-ridden the neighborhood was and will not be coming back in a hurry. Unless of course you will be primarily attracting the young, educated and professional crowd. If so then forget about the stigma as it likely won't matter much. They will just be concerned that this are places to eat, shop and do it safely. Which brings us back to the cooperation of trendy businesses, the local government and the police. Without them signing on, imo, this doesn't happen.
You will also want to get together with the responsible tenants in the area and encourage the start of homeowners associations. Your challenges will be to get them to work together to clean up the neighborhood. Some might be fearful of the criminals. Others may actually be housing them as family members and friends. Start with the responsible and brave ones first. The ones who don't give a damn about a drug dealer and will smack the lights out of one like he was his son. Get enough of them together and you can clean up a neighborhood. Again, this is a LOT of work.
Finally, check with the city's 'Master Plan'. Every major city should have one and it should tell you the path of improvement (there's actually a term for this which I can't remember right now) the city will take in the coming years. You may find out that the city already plans to start revitalizing the area in 5 years.
These are just my thoughts.