No matter which chat application you're using for your business, its success depends on how you organize your team. So, before selecting a chat app, make sure your team organization is in place.
So, let's get started and check out the features and functions of these powerful chat applications built specifically for businesses and professionals. Take your time in thoroughly testing each one of them.
Gitter - If you're a developer using Github on a frequent basis, this chat solution is perhaps the best option for you. It's made for developers and programmers with a powerful free plan. With full Markdown support including syntax highlighting, you're equipped with all the features to easily converse about and share your code snippets. It can tightly integrate itself with dozens of useful services and tools used by developers around the globe. I use it myself and found it absolutely user-friendly and immensely valuable. I'd highly recommend using its web-based version.
Flowdock - This powerful chat app is built for professionals that integrate both email and chat features into one service. Whether you want a private chat session or looking for support of threaded conversations, this app provides flexible ways to communicate with your team. You can use it both on the desktop and on your mobile device. You can even use it with a typical IRC client. You can link chat users to a conversation to grab their attention. You can even use hashtags and can filter all the conversations accordingly. It also provides integrations with useful 3rd party tools.
Slack - It's an all-in-one communication platform for teams of professionals with some of the most impressive features. You can create dedicated chat channels for different issues, projects and topics that can be shared with the entire team. Apart from regular text, you can share audio, video, files and your resources on popular cloud storage services. Its advanced search mechanism can easily mine out useful conversations relying on context instead of plain keyword search. You can also use its powerful and handy auto-complete feature to speed up your conversations. 
HipChat - This professional chat application for professionals can be used on different platforms and mobile devices. Apart from using native apps, one can also take advantage of the web version. It also supports screen sharing and flexible video calls for the entire team. Like other professional chat apps, this one also supports the integration of dozens of useful services built for professionals. All the conversations are encrypted and secure. While using it from multiple devices, you can find all your conversations synced. It has one of the nicest interfaces among all the apps listed.
Campfire - This is yet another useful business chat application that's ideal for developers and professionals. Developers and programmers can easily code in real time in a collaborated form through this powerful communication medium. It also supports conference calling for easily conducting remote business meetings. Since it is a web-based service, you can easily use it on any platform. A native iPhone application can also be used while you're on the go. You can also integrate various 3rd part extensions to add more features in this powerful business chat application.
ChatWork - The name says it all! This chat application has several useful features for a team of professionals. It has a user-friendly interface with loads of flexible features like easy file sharing and group-based threaded conversations. It has a useful notification system to keep you up-to-date about the conversations. Each user can customize and maintain his profile too. It also includes complete video calling support. It also has a handy task assigning and tracking feature where every group moderator can track essential business tasks assigned to all the team members.
Office Chat - As the name implies, this chat application is ideal for office environments where a large team of employees can easily converse in a secure manner. You can do real-time group and private chat through this app. It supports a powerful instant notification system to keep you in the loop with any delays. And when it comes to sharing multimedia content with other participants, you can take advantage of drag and drop support. It also ensures peer to peer message delivery confirmation. All chat histories are archived for an indefinite period for easy searching.
Teamchat - This feature packed business chat application works seamlessly across all the devices no matter where you are. It can filter important messages from a large conversation to provide useful insights vital to your business. It has a unique chatlet feature that allows you to integrate various small features and tasks instantly. You can also create common workflows that can ease the execution of common and repetitive tasks during the conversation. Its web version works efficiently on all modern browsers. You can also vote messages in the entire threaded conversation.
Flock - The last app in this list is by no means inferior than the apps mentioned above. One of the most striking features of this chat app is its slick interface. It has a central public lobby group where you can instantly broadcast an important message to the entire team. Administrators can maintain the profile directory of all the team members. It has both native apps for all common operating systems as well as a handy web version. All the business communication done through this application is completely encrypted and secure from hackers or intruders. It's worth giving a try.